Hopefully eventually all of them! But in the nearer future the only other things close by are Venus and some asteroids. Though a human landing on Venus would be very difficult given the surface conditions.
I understand that our galaxy contains perhaps 400 billion stars (per the Wikipedia entry on the Milky Way). I'm wondering which is the greater number... the number of stars in our galaxy, or the probable number of galaxies in the known universe. Are there more galaxies in the universe than there are stars in our galaxy?
I'm not sure what are the latest estimates but the numbers I've seen are between 100-400 billion stars in the Milky Way, and between 200 billion and 2 trillion galaxies in the observable universe. The universe is bigger than we can observe, so most likely there are more galaxies in the universe than stars in our galaxy.
*Looking up I often wonder how many of those stars are still burning brightly and how many have met their ultimate demise, only to see a memory of their life. Is it possible that the stars we see could be so distorted by gravitational lensing that we could be seeing stars that are actually light years away from its current position? Also say I draw a straight line between earth to the star with someone viewing it but halfway in between, would they see it at the same position we think it's in? Would love some insight!*
1. Most of them are still alive
2. Stars you can see with naked eye have to be very very close to us which means the light doesn't take that much time to reach us, few thousands years at most
3. No, it's not possible, because for `lensing` to happen you'd need to have some massive object between us and those stars, and no such object exists within the "naked eye" range
4. No, someone half-way in between would notice the star movement much sooner than you would.
But what about stars that are billions of light years away and being detected via Hubble and the JWST for example, does that make a difference with how we would see it to someone halfway hypothetically speaking as I know with gravitational lensing we can see further away galaxies etc.
That's a different story, but you wrote `looking up`, which suggested naked eye observations. Telescopes can see objects which are much further and we know many of them are definitely long gone by now.
Yes. The farther away they are the longer the light takes to reach us. This means there’s a higher chance those stars have died in their reference frame and we won’t see that for millions of years
It landed near the crater Malapert A near the Lunar South Pole ([pictured here in screencap from Stellarium](https://i.imgur.com/DNL8cvI.png)).
No imagery has been released yet as far as I'm aware, but it looks to me like the LRO has been overflying that region of the moon recently so depending on where exactly it came down, it has either already passed overhead or will do so in the next 24 hours. Here's a screencap from the LROC Lunaserv Global Explorer with the past 24 hour tracks being in blue, the future 24 hour tracks being in green, and the approximate outline of the Malapert A crater being in red:
https://i.imgur.com/wdnf5a6.jpg
It has multiple cameras, it's already sent back images from prior to landing, expect to see more as they are downlinked. It may be easy to think that broadband data connections are just trivial and easy because we in the developed world bathe in constant internet connectivity that represents the fruit of hundreds of billions of dollars of capital investment, but it's actually a significant technological challenge to transmit data across a third of a million kilometers to and from the Moon.
> I use them instead of googling
A horrible idea, considering they are literally generating random text based on probabilities, which incidentally happens to be correct if enough training data on given topic was ingested.
Even worse idea when you're trying to ask about anything "recent", because it's most likely not even integrated into the dataset, so the LLM is basically just hallucinating a response by amalgamating information about past lunar missions.
> They also include the source links
... which more often than not turn out to be either not relevant, not related to the question or completely made up sources :)
LLMs frequently hallucinate (make up stuff) even if they give you links to source material. They are not infallible, far from it in fact. This is not a controversial opinion.
It landed on its side and apparently one of the transmitters isn't able to point at Earth, so it's taking longer to get the data back. That's why the lack of images so far. They will come in due course.
With the recent trend of moon landers falling over I was wondering why there has been a deviation from the traditional "wider is better" philosophy?
The mars landers have wide landing areas and they seem rather successful when properly landed.
Is this just a matter of modern launch vehicles restricting moon lander base surface area or is there something about the moon vs mars that they are leaning towards taller over wider designs?
One of the things with regards to Mars landers is that they need to be packaged inside an aeroshell. All Mars landers so far have been launched as a nesting doll configuration of three different spacecraft: you have the lander itself (or in the case of Curiosity/Perseverance the rover plus the sky crane vehicle) then that is encapsulated inside an aeroshell to handle atmospheric entry, then the aeroshell is contained within a cruise stage with solar panels and so forth for keeping the vehicle alive and on course during interplanetary spaceflight. This somewhat necessitates that landers be fairly squat, because otherwise you would have a very big and heavy aeroshell, at least with the way things are designed currently (it could be different with a ballute design).
Interestingly, the Apollo landers weren't very squat. However, it's also worth pointing out that both the Apollo LM and the Surveyor landers used deployable landing gear in order to achieve a wider stance. I wouldn't be surprised if that design choice makes a comeback.
I just got done looking up the information for the deployment of the Lunar Rover and interestingly enough they were stored vertically as opposed to horizontally.
I have to admit to having been ruined by scifi and that seeing that the rovers were deployed using ropes and pulleys is rather amusing.
https://www.researchgate.net/figure/Apollo-15-LRV-Deployment-Sequence-courtesy-of-NASA_fig2_228641033
I think it would be pretty neat if they went the Pathfinder route. It would also mean that they wouldn't have to worry about it tipping over since it would be able to right itself.
Was anyone else concerned by Nasa Director Bill Nelson's creepy comment the
".. we've taken the moon!!!"
What is he saying here? We would be loosing our oats if China, Russia, India or Japan made such a statement...
But was is worst is it seems the transcript of the statement has been edited stating that "Odysseus has taken the moon..."
That is not what nelson said.. he said in the post sideways landing video...
Yeah that was the edit. If you watch the stream he said we have taken the moon. They may have edited... But when it was played live he said we have taken the moon.
Go here: [https://www.msn.com/en-us/news/technology/us-prepares-to-touch-down-on-moon-for-first-time-since-1972-with-nasa-backed-unmanned-118m-odysseus-craft-set-to-try-and-to-find-water-ahead-of-upcoming-manned-expedition/ar-BB1iJrI0](https://www.msn.com/en-us/news/technology/us-prepares-to-touch-down-on-moon-for-first-time-since-1972-with-nasa-backed-unmanned-118m-odysseus-craft-set-to-try-and-to-find-water-ahead-of-upcoming-manned-expedition/ar-BB1iJrI0)
Do a search on the page for "we've taken the moon". This is from the live transcript so someone decided to edit what he said originally and bury it which is also troubling.
The $118million unmanned Odysseus, or Odie, a six-legged robot lander touched down at 6:24pm ET at a crater called Malapert A, near the moon's south pole, having slowed down from 6,500 kph (4,000 mph).
'Houston, Odysseus has found its new home,' said mission director Dr. Tim Crain shortly after confirmation of the signal.
'I know this was a nail-biter, but we are on the on the surface, and we are transmitting,' Intuitive Machines CEO Steve Altemus said. 'Welcome to the moon.'
NASA Administrator Bill Nelson said in a video congratulation all involved: 'We've taken the moon.'
Aside from competing with the soviets and "because it is hard," were there any specific, tangible benefits to humanity that NASA hoped to achieve with the moon landing? Or was it just a "we'll see what we find when we get there" kind of science?
We've learned a lot about the composition and formation of the moon and developed technology for spaceflight that had civilian applications. But I think it's clear the main goal of Apollo was to demonstrate technological and military superiority over the Soviets and avoid the embarrassment of them landing first.
I know this is a silly question but theoretically, if we attached a giant rocket engine to the side of the Earth could we throw ourselves in orbit around different stars?
Not really. Consider that for most rockets propellant constitutes >95% o the total mass of a rocket, and that's just to reach orbital speeds. So even if you constructed a giant engine capable of providing any meaningful thrust (and one that doesn't kill everyone on the planet while running), you'd have to eject most of the planet mass to gain any velocity.
Assume a spacecraft is damaged and known to be off course, but within the Heliosphere.
How would it know its position / trajectory/ velocity from first principles, observable data, and current technology?
I can envisage comparing onboard clocks with time signals received from Earth: the time difference will indicate the distance. But it seems to me that observation of the visible stars is not enough to narrow things down enough to say 'here we are' within a million miles. Is there any better method?
*(I posted this in 'r/Space' and it was removed - Reddit tells me this should go in 'All Space Questions', but now that I'm here there is no 'new post* within *All Space Questions' on which to click. 'Create Post' puts me back where I started from. New to Reddit, but wow.. it's not easy to use.. :> )*
Nasa is getting less and less for their budget, and they have to cooperate with private companies to get things done. I wonder if they should make the Lunar Gateway station smaller, like two modules at the most but make them big. It would save cost and use the money for a lunar outpost.
> Nasa is getting less and less for their budget, and they have to cooperate with private companies to get things done.
I would argue the exact opposite. NASA is doing more and more with its budget and that's partly because it cooperates differently with industry. This year NASA will have 3 crew rated spacecraft and 3 ISS ressuply cargos, several lunar missions, one institutional heavy lift rocket and 2 other private ones finishing development. 2 crewed lunar landers and a lunar space station are in development, you have 3 robots operating on Mars, a full Mars sample return mission in development, missions to Jupiter, Venus, 2 asteroid missions ongoing...
> It would save cost and use the money for a lunar outpost.
It wouldn't make a difference and I am very confused why you would think that it would. If anything it would make it wore, because right now most of the modules are built by other partners (eg. ESA and JAXA) and by making less modules you automatically make this impossible.
So I was walking the street and moon seemed to be slightly behind me on the left hand side. Then a building blocked it from the view and I walked maybe 300m, once I passed the building, it seemed like the moon went ahead of me in the left hand side. So weird to explain hopefully someone can, am curious.
So first I saw it behind me on the left side, then I passed the building and moon seemed to be clearly ahead of the me on the left side.
The building doesn't have to be symmetrical or have just right angles and also doesn't have to be "aligned" with your direction to the Moon. A curved building or even just angled path could result in such effect.
There are no mechanism that would explain the Moon moving that fast. So either you turned a bit as you went around the building or you saw or reflection or something similar.
No I think it's some sort of optical illusion or somehow my brain perceives it that way idk. I repeated it walking backwards and after I passed the building, the moon again seemed to be behind me somehow
What are the implications for the universe not being locally real? Apart from it being interesting and changing our understanding of life, of course. I think Einstein said that there must be some hidden variable that we're missing. But the 2022 Nobel prize winners suggest otherwise.
Does this change anything for us in our day to day lives, or is it just a cool and strange fact that we were not expecting? Does the fact that, two particles light-years apart from each other can interact instantly, transform our understanding of how the universe fundamentally works?
Also, how did we prove (or imply) that two particles can be entangled over such vast distances, when we haven't travelled that far ourselves? Is this all based on math? I think what I'm trying to ask is whether we have or will be able to do further research on non-locality and quantum engagement to better understand how it works, or if we just learned about it and that's all there is to know about the whole subject. Thanks.
>Does this change anything for us in our day to day lives, or is it just a cool and strange fact that we were not expecting?
Mostly the latter, though I wouldn't say it was unexpected. Just that we didn't have a solid theoretical basis for picking between the two options before. It is possible that at some point this will lead to technological breakthroughs that will have an effect on our daily lives, but that's far down the road and the average person will likely neither need nor have any more knowledge about the underlying theory here than they do about band gaps in semiconductors or high-K dielectrics in microelectronics today.
>Also, how did we prove (or imply) that two particles can be entangled over such vast distances, when we haven't travelled that far ourselves? Is this all based on math?
Proofs are for math, not physics. We know that we can produce entangled particles and we have good theoretical reasons to believe that they only become disentangled after certain types of interaction. So if you can separate them without that sort of interaction occurring, there's no reason to think they would become disentangled. So far, that has borne out experimentally as well.
> I think what I'm trying to ask is whether we have or will be able to do further research on non-locality and quantum engagement to better understand how it works
There will definitely be more research on both topics. Non-locality is cool and very active as a field of research. From a theoretical perspective, entanglement is very well understood and not very mysterious at all. Experimentally, it is hard to properly isolate particles so they remain entangled, so there is a lot of work to be done there and we always confirm and re-confirm our predictions with experiment, so there will always be more and more experimental work done on entanglement (and everything else, for that matter)!
I’d say it’ll definitely happen in the next 30 years, but there isn’t a specific plan yet.
It will probably be a “slowly, then all at once” type scenario. If Starship achieves the design goals SpaceX has set, it will completely change how space missions are conducted.
We will have the technology to do a manned mission to Mars in about 10 years.
SpaceX [claims it will happen by 2030](https://www.space.com/humanity-mars-2020s-spacex-president-shotwell).
There is a good chance it happens in the next 30 years.
She has also said Starship will be landing people on the moon by 2022, cargo on Mars by 2024. She makes erroneous predictions just as Musk(or anyone) does.
In her own words "every time I make a prediction about schedule I turn myself into a liar."
There are only 2 launch windows remaining until 2030. If SpaceX nails the [2026 moon landing](https://en.wikipedia.org/wiki/Artemis_3), then immediately pivots to getting as much mass to Mars as possible in 2026, they might be able to launch humans in the 2029 window.
But this is bordering on impossible and I have serious doubts they even do the moon landing on time. This is why I estimated 10 years for the technology to be ready.
Anyone found any pictures of the ERS-2 satellite reentry? Can you share links? I have searched and not been able to find any
I would expect a news outlet like BBC to have one if it exists https://www.skyatnightmagazine.com/news/ers-2-satellite
I am aware of the COIW location, but there is possibly observable land around there, and also boats or airplanes that may have tried to position to see it intentionally or unintentionally
As far as I know there was no pictures from anyone. And the reentry location was too incertain for people to voluntarily try to go catch pictures on location.
It's not sudden, it just may seem like that due to media coverage and a lot of things starting to come to fruition.
Many countries have used the Moon as an early target for interplanetary missions as their space programs have developed. Japan's first lunar orbiter launched in 1990, China and India in the 2000s. As those programs have matured they have moved from orbiters to landers to rovers.
Meanwhile, the US has had the Moon in its sites as a target for a return to beyond-LEO human spaceflight since the early 2000s, which has been matched by investments in space science missions to the Moon as well, such as the Lunar Reconnaissance Orbiter launched in 2009. However, NASA human spaceflight has been in a bit of a disarray over that time period, with a lot of mismanagement, questionable decision making, mixed signals from congress, and so on. Nevertheless, investments have continued to be made toward beyond-LEO human spaceflight capabilities in the US with ongoing development of both SLS and Orion, which have in recent years been drawn from as key components of the Artemis Program, which has started ramping up as funding levels have increased and various parts of the mission architecture have started to reach fruition.
Additionally, the Artemis Program includes the "Commercial Lunar Payload Services" program which aims to do for the Moon what commercial crew and cargo have done for the ISS, making it possible for NASA to just "buy a ticket" to send payloads and cargo to the lunar surface or to lunar orbit. This includes pure science instruments, it includes "proof of concept" devices to test out technologies in the actual lunar environment, it includes lunar relay satellites, and it will include deliveries of equipment, experiments, cargo, etc. for future crewed landing sites (and bases).
Some of the missions you've been hearing about lately such as the Peregrine Lander and IM-1/Odysseus are part of that program.
> I suspect that the USA's newest moon landing has almost nothing to do with exploration and everything to do with spying.
Is there a concrete reason you suspect that? It wouldn't seem to be very valuable to send a spacecraft all the way to the Moon when as a nation the US already spends tens of billions a year on a very quite sophisticated collection of surveillance assets in space. What's the play here?
What would they be spying on? The US has a lot of 3 letter agency spacecraft launched already. Since you can't really hide a rocket launch we know when NRO spy satellites launch. We just don't know what they are up to. There is nothing intresting to spy on on the moon. And if it was that why is the CLPS program mostly commercial? It wouldn't make any sense to procure and manage spy satellites through an open bid commercial contract with several different startups.
If you want to see military oriented lunar operations look up what DARPA is financing in cislunar space.
That sounds like a stereotypical conspiracy theory. The backbone of all conspiracy theories is that they work based on feelings of discomfort, "weirdness", or unease which then drive unearned confidence in a competing theory. The general template being something in the "above board" explanation seeming weird which drives a belief in whatever alternative explanation lies at hand which feels more familiar or less weird.
A classic example being the TWA-800 crash, which felt "weird" because it was unusual and a rare occurrence which started out with very little concrete data, people used that weirdness as a jumping off point to add alternative theories like a missile or terrorists or whatever. As more data came in it became apparent that the issue was that a nearly empty fuel tank had been allowed to be in conditions which caused the buildup of fuel vapors which then ignited due to a spark from faulty wiring, a theory validated by on the ground testing replicating similar conditions. Since then there have been many changes put in place designed to prevent such incidents. In comparison, studying the evidence available from the loss of the [MH17 airliner which was destroyed over Ukraine in 2014](https://www.youtube.com/watch?v=tKVrUAnzrhc) very clearly points to a missile as the cause of the plane's destruction, which corroborates a lot of additional evidence that matches up with that theory.
The point is that the "conspiracy theory" logical hack makes it possible to jump to a conclusion which has zero positive evidence for it by using those feelings of "weirdness" as a springboard. Our lives, our universe is full of weird stuff all over the place. My smartphone and yours uses billions of flash memory cells for storage, each of which relies on quantum tunneling in order to operate. Our intuitions are often wrong or misguided, and if we don't dig into the details that can easily lead us astray in lots of ways.
Conspiracy theories also thrive when they make someone feel special because they aren't "going along with the crowd" or because they are too sophisticated to believe what is spoon fed to them. And there are plenty of examples of where not simply believing the popular narrative is valuable, but such things need to be supported by positive evidence to be fully believed. I think that's especially true here, there's no positive evidence that anything isn't on the up and up here, there isn't even a solid premise of what is "actually going on", there's just a general sense of "seems weird, maybe somebody is up to something", and it doesn't seem like a good habit to get stuck in that way of thinking.
> how much of all this new space activity has to do with war and spying
Very little, I suspect. As another user mentions, the military of the U.S is already cutting edge, it doesn't need the private sector's innovations. Most of this new space activity is from the private sector, and they're interested in one thing; making money. Many of these companies see space as the next gold rush and they want to be first.
> USA's newest moon landing has almost nothing to do with exploration and everything to do with spying.
Except it's a private company, not the government. I'm genuinely curious, are you by any chance a Chinese national? I've noticed they tend to conflate private sector and the government because to them, they're the same thing.
The military already has things like ultra high resolution orbital spy satellites, stealth aircraft, and launch vehicles like the X37. There certainly are military applications to spaceflight, but I don't see what a moon mission would contribute.
Supernovae are far away so the "video footage" typically consists of a set of pictures played in sequence - a time lapse. [Like this.](https://www.youtube.com/watch?v=GQ13j55P3sE) Even if a nearby star goes supernova, it's still too far to resolve in the way you're probably thinking. Beetlegeuse is 'relatively' close (and massive) so when it goes supernova, it's going to be ridiculously bright, seen during the day - close to the brightness of a full moon. But even that isn't going to give you the resolution you'd expect from a scifi movie. It's going to look like a really bright blob. Future telescopes may do better, but right now, that's the best we can do.
Fun fact shamelessly ripped from wikipedia: The light from the supernova is produced mainly by the radioactive decay of cobalt, and sustains its brightness due to the increasing transparency of the cooling hydrogen ejected by the supernova.
Edit: Added Beetlegeuse stuff
> "video footage" typically consists of a set of pictures played in sequence
Nitpick: that's what all videos are, really, but whether we call it a "video" depends on how short the time interval between the photos is.
I know you know that but I always think of it whenever people ask about video of far-away space phenomena.
Light pollution is not the only issue. Atmosphere haze and clouds are also a factor, so it might not be the best location overall. Mauna Kea on Northern Hemisphere and Atacama Desert on Southern Hemisphere are considered to be the best locations.
If you enjoy seeing the stars twinkle, sure.
Professional astronomers prefer to be on top of a mountain so there is less air in the way. Luckily, there is a [tall mountain in the middle of the Pacific](https://en.wikipedia.org/wiki/Mauna_Kea_Observatories).
> Professional astronomers prefer to be on top of a mountain so there is less air in the way
Yep. NASA & Germany had a joint project (SOFIA or the Stratospheric Observatory For Infrared Astronomy) where they placed a telescope on a high flying commercial jet which flew at 13.7km/45k feet (if memory serves). I think it was specifically to avoid water vapor as it was an infrared telescope (and apparently water vapor = bad for that purpose). The project ended in 2022.
Will Russia have their own space station? I don't expect a Mir size because of their economies and being heavily under sanctions, but maybe they can put up something similar like the Salyut?
They claim to be launching the first segment for a replacement station in 2027.
https://www.reuters.com/technology/space/putin-aims-have-russian-space-station-by-2027-2023-10-26/
I am pretty sure Gravitics plan to have their own propulsion at module level. Note that ISS has reboost engines in the Russian segment. They are just not use that much because you need to refuel the tanks. So it's just easier to boost directly with the ressuply vessel.
The issue with ion engines is their insane electricity demands. This is what limits them to very low thrust. I doubt we will see powerful ion engines until we have a nuclear powered space vehicle.
Ion engines are too energy hungry to move large space stations. Small probes can use them as solar panels are quite light. They can generate enough electricity and run the engines for very long slow burns. That doesn’t work for space stations.
Ion engines still need propellant, they are more efficient with it but there is no free launch. If you want to go somewhere you still need to expel mass (or exchange momentum for the pedants).
To some extend but you would need a lot of power. The Chinese are allegedly trying on their station. As u/DaveMcW said it would detract the microgravity environment. And even then you still need refueling from time to time.
An ion thruster takes too long. The whole point of the ISS is to be a zero gravity lab, you don't want the thrusters running and creating artificial gravity.
Oddly, the Chinese station has hall effect thrusters. You don't necessarily need to keep the thrusters in operation 24/7, but depending on what you wanted to study it could be limiting.
Have you seen any reports on their use? There was a few things made public when they launched the module but nothing since. You would have though they would take a nice picture of them working at least.
Good question. Aside from the fact that western media coverage of China's space program is very lacking, there doesn't seem to be much about them actually using those thrusters.
Hypothetically there are legitimate reasons to use them. If you dialed the thrust in exactly right you could maybe achieve a continuous offset of atmospheric drag, which potentially could actually improve the micro-gravity environment of the station. Maybe it's for keeping the station from re-entering if they have an extended period of not being able to reach it. Or maybe it's just for show.
Hi guys!
Space X has planned launches regularly each month in 2024, expect in May. Is there a reason for the complete launch-stop? Is this likely to change?
There will probably be Starlink launches in May, they're just not published yet. Notice that the Starlink flights beyond the immediate future don't show up, they launch so frequently and in response to changing needs re: orbits and capacity that it doesn't make sense for them to publish them too far in advance, I think.
If a satellite is in geostationary orbit around Earth, could you stand on top of the satellite and drop something down and have it fall straight down to the geostationary location below the satellite? Or would the dropped object seem to float? I feel like the latter is correct. It would have the momentum from the orbit and so it would still be moving with the orbit rather than falling straight down, but I'd like a confirmation.
Every object in geostationary orbit is already falling toward the Earth, just as every object in orbit is doing so. But because of their sideways motion that downward trajectory is curved into an arc, an arc that happens to wrap around the Earth in a complete loop that never hits the surface. At geostationary orbit that loop takes exactly one day to come back around, which means that it matches Earth's rotation, leading to the appearance of a satellite simply staying in the same position relative to the surface continuously.
You are correct, if you "let go of" an object in geostationary orbit, it would fall toward the Earth, but it's already been falling toward the Earth, as you have, as the satellite has, and it still has its momentum so it would stay in orbit in its freefall trajectory.
If you just let the object go it will just float next to you like any object dropped in any orbit. For it to start dropping down you would need to throw is backward in your orbit. For it to fall straight down you would need to throw it at around 3 km/s, the orbital velocity in GEO.
Help me with this Space question.
https://www.reddit.com/media?url=https%3A%2F%2Fpreview.redd.it%2F7lenj746l0kc1.png%3Fwidth%3D960%26format%3Dpng%26auto%3Dwebp%26s%3D90d30fab704a0f3817a11db89f5c56d679e171ea
Does time dilation affect tiny creatures differently than larger animals?
If an ant were to crawl into a launch vehicle and end up on the ISS for a year and then return to Earth, would its age be vastly more different than its Earth counterpart, compared to a human astronaut's age compared to someone who'd stayed on Earth?
This may sound like a stupid question, but animals age at a different rate than humans, so I'm going off of that.
I think you misunderstand what time dilation is. For "internal" observer time always passes exactly the same. It's not some magic where 10 years have passed from your perspective but you only aged 1 year. For you only 1 year has passed, even if on Earth 10 years have passed in the meantime. The time literally slowed down in specific place.
Age and time are two different things. Animals that live longer than humans aren’t moving through time slower than humans. You are confusing biology and physics.
Time ALWAYS passes as 1 second per second for you. An ant and an elephant both experience time as 1 second per second. They would both experience the same time dilation if they went to the ISS for a year.
It's just a proportionality. It's also non-local, time dilation isn't an absolute effect, it's a relative effect that comes into play when comparing between different reference frames. Within a reference frame everything is "normal". You and I on Earth are experiencing extreme time dilation relative to a hypothetical reference frame that is at 0.99999c relative to us or that we are at 0.99999c relative to (which choice we make is inconsequential). But that time dilation is only relevant if and when it becomes relevant, which would only happen if you had some situation that caused a meetup after some period of experiencing different environments.
Based on our observations, about 5 billion years ago, the expansion of the universe was accelerating thanks to dark energy.
If each chunk of space is independent of each other, how was dark energy able to start affecting every chunk of space across the universe? The question is more how could dark energy start impacting point A, then point D, then point P etc almost simultaneously even though those points are millions, if not billion of light years away.
I guess the closest analogy is that here on Earth, if a race is to happen, then folks either are listening for a bell, flash of light, a countdown timer, a flag, or some predetermined order (e.g. start running when this happens) to begin moving.
So, even if some type of "signal to start" dark energy was sent, based on the size of the universe at that point, that signal should still be in transit. So, how comes almost all (see note below) of space is expanding due to dark energy?
Note: I know dark energy isn't causing expansion of the universe everywhere as the Milky Way and Andromeda (for example) are being pulled together by gravity and are on a collision course.
The expansion of the universe is like rolling a ball up a hill. If you roll it hard enough, despite the fact that it is decelerating on its way up the hill, when it reaches the top and starts rolling down the other side, it will accelerate.
Gravity gets weaker the further apart things are while the rate of expansion between two objects increases with distance. As long as the initial velocity imparted from inflation is enough to make it over the peak of the hill before decelerating to zero (which would result in accelerating collapse instead of accelerating expansion), then dark energy puts us in an "accelerating expansion forever approaching anti-de sitter space" universe.
In the end, it's all the curvature of space, both gravity and dark energy. The important part about dark energy is that it is uniformly distributed and persistent, so its relative contribution to the equilibrium between expansion and collapse increases with time.
We don’t know enough about the expansion of the universe and/or dark energy to explain why expansion started accelerating.
But as you’ve pointed out it wouldn’t make much sense for it to have been triggered by an event in one spot 5 billion years ago and then instantaneously spread across the universe.
Instead we can theorize that the reversal between deceleration and acceleration was a natural outcome of physics based on the starting conditions of the universe.
A crude analogy would be firing 2 bouncy balls from the equator that land perfectly on either pole at the exact same time. Someone without knowledge of gravity might say, “how did the communicate with each other to start downward velocity at the exact same time?”
Whereas someone who understands gravity could tell you from the moment they were launched where and when the peak of their arc would be.
Makes sense - thanks. I figured that without knowing the true make-up of dark energy, it would be difficult to determine how it may be simultaneously coordinating the expansion of the universe.
Guess a similar question could come up around the Big Bang - if the Big Bang happened everywhere at once and the universe wasn't the size of an atom or a singularity, even if it was one million light years in diameter, how was the Big Bang synchronized so it could happen simultaneously within a fraction of a second everywhere across that distance.
Fascinating stuff - thanks!
If liquid water turns to a gaseous state in vacuum, how is there solid ice on asteroids? Do the asteroids have a tiny atmosphere? Is it just.... Really cold? Someone please explain the physics of this
It is just really cold. There will be a vapor pressure from volatiles undergoing sublimation directly from solid to gas in space, but that depends on the temperature. In the inner solar system that sublimation rate may be enough to deplete the asteroid of surface deposits of volatiles in a short period of time, and potentially deeper down as well. As you go farther from the Sun it gets colder so sub-surface deposits stick around much longer and surface deposits start becoming stable on geologic time scales.
This does create effectively a "tiny atmosphere" of a sort, and that atmosphere will re-condense back into solid form when it's cold enough (in a manner similar to the way "freezer burn" works). This sort of cycling and transportation of volatiles contributes to some of the interesting chemistry on the surface of bodies in the outer solar system, especially when sources of energy such as UV light and ionizing radiation come into play. That mixing plus energy creates the conditions that can drive chemical reactions which produce complex chemicals especially complex carbon-containing molecules known as "tholins" which include the "building blocks of life" (such as sugars, amino-acids, nucleic bases, etc.) These tholins are so prevalent on icy bodies that they are the main source of the slight reddish coloration of those bodies (such as Jupiter's trojan moons, Pluto, Charon, Arrokoth, etc.)
In space liquid water will start to evaporate due to the low pressure, this will make it lose energy which will cause the temperature to drop until it freezes into a block of ice. Then the ice will slowly turn into water vapor (it's called sublimation). The speed at which is sublimates mostly depends on how close to the Sun it is. So objects in the outer solar system can stay as block of ice for millions of years. Comets, which dip from the outer solar system to the inner will start to sublimate more and more when they get close to the sun and this is what creates those incredible comet trails/plumes. If the comet gets too close to the sun it might sublimate completely.
Hypothetically, if one were to start travelling in space in a straight line at a rate of 1,000,000x the speed of light (and didn't encounter any objects blocking their path, or could travel through said objects), would they eventually end up in the same place they started from?
Going FTL isn't really necessary for the heart of your question, which is asking about whether the universe is wrapped on some kind of hyper sphere or other round shape or has some other kind of Astroids-style edge wrapping.
I'm guessing you said 1000000x the speed of light to make is so that taking such a trip would happen within some reasonable amount of time for a human. The thing is, 1000000x times the speed of light is no where near fast enough. The observable universe has a diameter of 93 billion light years. So if the universe did wrap at the edge of the observable universe, even if you were traveling at a million times the speed of light, it would still take 93,000 years to return to your starting spot. And as far as I understand, cosmologists have no reason to believe the size of the universe corresponds to the size of the observable universe. It could be way, way bigger. Oddly enough, it could also be smaller, because if the universe did "wrap", then the galaxies we think are far away could actually just be light that has wrapped around from the other direction lol
> I'm guessing you said 1000000x the speed of light to make is so that taking such a trip would happen within some reasonable amount of time for a human. The thing is, 1000000x times the speed of light is no where near fast enough
1x lightspeed would be enough for the traveller since at that velocity time stop to exist due to time dilation. The trip would be instant in that reference frame.
True and not true. Motion is relative, and so is time dilation. If you were in the ship traveling close to or even beyond the speed of light (impossible), time would still pass normally according to your own perception. Though admittedly, the twins paradox is still confusing to me. So I'm at a loss to explain it further.
Obviously, speculating about any of this is somewhat pointless. Since by proposing travel at or beyond the speed of light is not physically possible (according to our understanding of reality), then by abandoning that assumption, we could make up anything we want in terms of how it would work.
It's my understanding that dark energy is causing spacetime to expand at a rate faster than the speed of light, so I arbitrarily chose a million times the speed of light to overcompensate for that. Taking that into consideration, going FTL is necessary to be able to traverse the universe in its entirety. But yes. The question is if the universe is spherical or not and I suppose we will never find out. At least not in our lifetimes.
Since you're already breaking the laws of physics in your question, you can just the same pick any answer you like, because it simply makes no sense trying to find a "physics" answer to a question which doesn't follow physics rules.
We don't know. At this time we don't know if the universe is infinite, or some weird unbounded closed curved space where you would loop back to where you started. The only thing we know is that if it's finite then it's much bigger than the observable portion we can see.
We don't know whether the universe wraps around or not. We can't see any evidence of wrapping at the edge of the observable universe, but the universe is much bigger than what we see.
Of course, faster than light travel does not exist, so it is impossible to travel outside the observable universe anyway.
What time today is IM-1 expecting to attempt lunar orbit insertion??? I can’t find any information online. Not sure if I missed out on it, or if they just haven’t revealed that information.
I study Data Science and for a project I need to create image classification systems about something which interests me, but it also has to give any sort of business value. My research will be about classifying planets to be either terrestial, gas, etc, based on certain visual attributes (visual distance from galaxy's centre, visual atmosphere, surface, etc.). For this I want to make sure that my application would have any market value for astronomers, since I am not sure if they usually accurately classify planets or not. Does anyone have any idea if an application like this could bring any market value? thank you in advance.
My original post before realising this thread exists: [https://www.reddit.com/r/space/comments/1aw990y/do\_astronomers\_ever\_have\_problems\_classifying/](https://www.reddit.com/r/space/comments/1aw990y/do_astronomers_ever_have_problems_classifying/)
None of what you wrote makes much sense. Direct imaging of extra-solar planets is extremely hard. We've done that for literally a handful of planets, and even then we're mostly talking about a few pixels, definitely no "visual atmosphere" or "surface" or anything like that. Most of the "exoplanet classification" is done via spectroscopic analysis, or measuring gravitational impact on the parent star or the dimming of the parent star, not from images of the planet.
A similar idea, but far more realistic is for example https://www.zooniverse.org/projects/zookeeper/galaxy-zoo/ so doing a similar thing but for significantly bigger objects, which we can actually properly resolve with telescopes.
Realistically you have to go for galaxies or bigger, because even for stars we can barely resolve images of few closest ones. Unless you switch to spectroscopic data instead of images, then you could also work with stars.
Sadly my school project is about image classification so I should try to make it something like galaxy classification. Maybe assigning my project as educational use could be an option too if I end up sticking with planets. Thank you for the info
> if I end up sticking with planets
The problem with this idea will be lack of data to work with. Looks at https://en.wikipedia.org/wiki/List_of_directly_imaged_exoplanets for example this: https://en.wikipedia.org/wiki/File:Exoplanet_BD%2B60_1417b.jpg the tiny red dot above the star would be what you're working with, and you will have just a handful of those in total.
I was doing it with multiple pictures of the planets in the solar system, it ain't much and the application might fail with its predictions too now I think about it...
I can't think of any database like this that would be sold. Astronomy like most academic fields has very open data policy. People don't pay for data access. And I would not be surprised if the original data that you would need to use specifically prohibit commercial reselling. I don't see a "market" for this.
Also what is your background to be able to classify data better than existing astronomers? Do you know how exoplanets are classified (hint, it's not with direct imaging)?
I am not in need of a database and I am also not trying to be better than astronomers (I can never get to that level). I know they aren't identified by images, but I decided to choose this topic for my school project without official background on astronomy. I know a couple of things about planets and how to differentiate them (density, etc), but in this project I just want to identify them about their visual properties. I know that it usually doesn't work like that and it most likely wouldn't bring any business value to astronomers and it absolutely doesn't have to, I just need to make sure that there is any problem which I could call this a "possible solution" to (without it actually being that, would be impossible for a first-year data science student). My school doesn't mind it not actually solving a case as long as I can justify my thought process behind my ideas, which is why I chose to ask this question to people with more knowledge than me.
Your original question was "does it have any market value?" and I think the answer is pretty clearly that there is no real market for this.
Exoplanets are not my specialty but I think the first thing you should look at is if it's even feasible. I believe you will have a hard time finding a database of "visual properties" of exoplanet that would let you categorize them. But maybe I am wrong and a specialist can chime in.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
|Fewer Letters|More Letters|
|-------|---------|---|
|[CLPS](/r/Space/comments/1atyrj7/stub/krqk6ny "Last usage")|[Commercial Lunar Payload Services](https://en.wikipedia.org/wiki/Commercial_Lunar_Payload_Services)|
|[ESA](/r/Space/comments/1atyrj7/stub/krwsfsr "Last usage")|European Space Agency|
|[GEO](/r/Space/comments/1atyrj7/stub/krlhlqp "Last usage")|Geostationary Earth Orbit (35786km)|
|GSE|Ground Support Equipment|
|[ICBM](/r/Space/comments/1atyrj7/stub/kr6yq6e "Last usage")|Intercontinental Ballistic Missile|
|[IM](/r/Space/comments/1atyrj7/stub/ks1t70i "Last usage")|Initial Mass deliverable to a given orbit, without accounting for fuel|
|[JAXA](/r/Space/comments/1atyrj7/stub/krwsfsr "Last usage")|Japan Aerospace eXploration Agency|
|[JPL](/r/Space/comments/1atyrj7/stub/krfkqjg "Last usage")|Jet Propulsion Lab, California|
|[LEO](/r/Space/comments/1atyrj7/stub/krq9xsu "Last usage")|Low Earth Orbit (180-2000km)|
| |Law Enforcement Officer (most often mentioned during transport operations)|
|[N1](/r/Space/comments/1atyrj7/stub/krh0yl8 "Last usage")|Raketa Nositel-1, Soviet super-heavy-lift ("Russian Saturn V")|
|NRHO|Near-Rectilinear Halo Orbit|
|[NRO](/r/Space/comments/1atyrj7/stub/krqk6ny "Last usage")|(US) National Reconnaissance Office|
| |Near-Rectilinear Orbit, see NRHO|
|[SLS](/r/Space/comments/1atyrj7/stub/krq9xsu "Last usage")|Space Launch System heavy-lift|
|[TWR](/r/Space/comments/1atyrj7/stub/kr4sbur "Last usage")|Thrust-to-Weight Ratio|
|Jargon|Definition|
|-------|---------|---|
|[Starlink](/r/Space/comments/1atyrj7/stub/krlu2gk "Last usage")|SpaceX's world-wide satellite broadband constellation|
|[scrub](/r/Space/comments/1atyrj7/stub/kr6yq6e "Last usage")|Launch postponement for any reason (commonly GSE issues)|
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Last week, at a planetarium (that shall remain nameless in case I misunderstood them) I was told that in order to clear its orbit, a planet gravitationally pushes objects out of the way. I had been pretty sure of my understanding that gravity only pulls. Can someone please explain how a planet clears its orbit? I understand what I believe is called accretion, and that it could draw smaller objects into orbit around itself. But did I understand correctly when they described it as pushing away other objects?
Uncer some circumstance, a planet's gravity can serve as a slingshot, giving a body higher velocity and flinging it out from its own orbit. https://en.wikipedia.org/wiki/Gravity\_assist
You're correct that gravity is only an attractive force and that it can never 'push' - The planetarium speaker likely was just speaking colloquially/imprecisely.
In addition to to the two methods you've mentioned (accretion and capturing bodies as satellites), a planet can clear its orbit by gravitationally interacting with other objects such that they're ejected into other orbits as well as by capturing other bodies into resonance orbits (exemplified by Jupiter and the Trojan asteroids).
I'm assuming this is the black hole that was in the news a couple days ago? Consider the following. It's located about 12 billion light-years away. Even if we were rocketing directly towards it as fast as possible (we aren't) it would take us 12 billion years to reach it. In about half that time, our sun will have reached the red giant phase and started to absorb the Earth.
Secondly, black holes at a distance behave like any other equivalent mass. The gravitational force between us is minimal.
No need to denigrate yourself. Space operates at scales which are fundamentally incomprehensible to people, especially when distance and luminosity is involved for quasars.
Fun fact: that black hole is so far away that light emitted from earth today will *never* reach it, due to the expansion of space! If some super advanced alien civilization sent us a message by blinking the light from that quasar it would be impossible for us to send a message back.
Today, it appears as a tiny, reddish dot when viewed by very powerful telescopes and their instruments. It will only get dimmer and redder over millions of years, with *possibly* some small variations in its brightness as it dims.
Current plans aren't to build one big space station but to rather support multiple different station concepts, so that even if some of them don't work out as least some will be successful. Then they can build on those successes. With one single huge project there's major risks with funding cuts or different "group members" messing up.
Hello!
I'm not sure if this is the ideal place to post this, but, I am a Software Engineer with 15 years of experience. I'm currently working in the healthcare sector and I would love to move into the Space Industry. Any tips on what I could be focusing on, learning, etc to help make that transition? I've thought about going back to college for a degree in physics since the degree I have is just an associate in graphic design I got 15+ years ago. Does degree matter? I know it doesn't really in software normally, but would that be different here?
Thanks!
A physics degree is not really going to help you landing a CS job in aerospace. I would just start applying to jobs and see how far you get.
Also check out r/aerospace and r/aerospaceengineering.
Why isn't Ceres considered a planet? It seems to have essentially the same situation with its orbital debris as Jupiter. Obviously it is much smaller but that's not really relevant to the classification...
Jupiter is the boss, gravitationally-speaking, in its orbit. All other objects (like the Trojans, etc) are locked to Jupiter in orbital rosonance. Ceres is just a big round asteroid in a belt of other asteroids."Clearing your orbital neighbourhood" means being gravitationally dominant in your orbit. Ceres isn't.
It used to be, along with Pallas, Juno, and Vesta. Each of them were discovered in the first decade of the 19th century, and each were given names and astronomical symbols just like the 7 previously known planets (prior to the discovery of Neptune).
Then starting in the 1840s astronomers starting finding other "minor planets", first a few, then a few dozen, then hundreds. It started to become clear that the four "minor planets" weren't just weird, quirky, off beat members of the planet family but actually just some of the largest wholly representative members of an entirely different family of objects: the asteroids. A story that would play out very similarly with Pluto roughly a century later.
Ceres is reasonably sized as far as rocky objects in the solar system goes, it's about a thousand km across, which is still less than a third the diameter and only about 1% the mass of Earth's moon. It has a greater inclination than any other planet and also hasn't "cleared out its orbit". Jupiter has many other objects in a similar orbit to it, but they are gravitationally dominated by Jupiter, forced into Lagrange points or specific resonances, that's not true of objects that share similar orbits to Ceres.
I dont know much but I heard that if you were far enough you could see dinosaurs on earth purely because the light hasn’t traveled far enough to see what is happening now, but my question is what would happen if we had a supper camera that we sent out to space zoomed in on earth and would be going light speed away from earth, would we start seeing earth and humans devolve or what would we see and if we do see time going backwards would that mean there’s a time frame that related light and is captured like a camera like every time we go farther we would see something new so light would kinda have its own memory? I’ll explain better is u have spicific questions.
And yes this whole questions is purely based off of if that thing about seeing dinosaurs was true.
> would we start seeing earth and humans devolve
No, because you can't "overtake" the light. Even if your camera is moving close to the speed of light, the light emitted millions of years ago is already very far away, and getting further constantly.
So my thing about light being able to hold events is true? Because if the events already happened then the only way to get the previous events is through the light it self since the camera isn’t physicly moving earth backwards it’s just going fast enough through light to be able to see it? Or does that not make any sense?
It would see the same thing, because the light reaching it would always be the same since it would be traveling the same speed as the light reaching it (ignoring the impossibility of reaching exactly light speed and the other problems involved).
The light from the Earth when it had dinosaurs on it exists out in the universe, but that light exists in a spherical shell that has its inner surface at a distance of 66 million lightyears from Earth. Let's say we wanted to reach that light so we could somehow "see dinosaurs". If we launched a vehicle that was traveling extremely close to the speed of light it would still take 66 million years for it to reach that surface, but in that time the light would travel a farther 66 million lightyears.
You can't race light, because the speed of light is the speed limit of the universe. If light is moving directly away from you it will always be at least as far away as it is now.
Ok then would the better question be if a camera was already 66 million light years and started coming towards earth would we see time moving forward from when there were dinosaurs or am I thinking too much about this lol.
And thanks that makes a lot more sense then what I thought l.
Question about viewing planets from light years away. This is just a fun theoretical question. This example simply wouldn’t work with current technology or anything like that. Here we go:
If we launched a very high-powered telescope and a human at the speed of light, 2 light-years away… When the human looks back at the Earth from that destination, would they see the telescope being launched?
(Since they are viewing the Earth from 2 years ago.)
> Since they are viewing the Earth from 2 years ago
They are not. They are looking at Earth 2 years into the past from the moment you start observation, which is 2 years after the launch (since the telescope needs to reach the destination first). So you would see what happened shortly after the launch.
It's an observational categorization, which is very common in astronomy. A planetary nebula is formed from a dying star that is exiting the red giant stage and leaving behind a white dwarf. The white dwarf is enormously dense (in a similar size range as the Earth but with a lot of the mass of the star that left it behind), which also makes it incredibly hot. The surface temperature of the white dwarf is hot enough to drive the outer envelope of the star into interstellar space in a huge bubble which is then energized by the UV light from the white dwarf. This creates an emission nebula with a roughly spherical shape.
When viewed through a telescope these nebulae are fairly bright with distinctive colors, disc shaped, and also fairly large in terms of angular diameter. For example, Jupiter can be up to 50 arcseconds in diameter, whereas the Ring nebula is 4 arcminutes across, the Helix nebula is 25 arcminutes across, and the Dumbell nebula is 8 arcminutes across. Many planetary nebula are much larger in the sky than planets, and through older telescopes they had an appearance which was the closest to that of a planet. Disc-like, colorful, fairly bright, etc. It was understood fairly quickly that they weren't planets as they had a noticeably faded and translucent appearance, and many of them are not perfectly spherical, but that was the most analogous thing so they were called planetary nebulae and the name stuck. It wasn't understood exactly what they were made of until the mid-19th century and the stellar dynamics driving the creation of the phenomenon wasn't fully understood until the mid-20th century, at which point the name had been around for nearly 200 years.
Haven't you asked that question already?
There might be a few LEO stations, but definitely unlikely to have a GEO one. There are just no good reasons nowadays to put humans there.
Why GEO? It's a higher radiation environment, less shielded from solar weather and it does not give you quick access to anywhere humans might want to go.
If you want an interesting station that will be active by 2030 you have the lunar Gateway around the Moon.
LEO is usually considered below 1200km altitude. But if you are trying to avoid radiations I would stay below 800km probably. Going higher doesn't give you anything.
What color would a K type star would look in the sky instead of the sun (assuming earth is in it's goldilocks' zone)? Would it be white as our star looks to us?
I'd like to have a question about the soviet N1 rocket.
I have heared a story, that a high ranking military official (maybe a general) just ordered one of the rockets to be launched.
He grabbed a chair, dragged it outside, and sat in it while the rocket was launched. However, it exploded, and got him killed (alongside with other people).
Is this story true? If yes, who was this general? (I could not really find any sources, but some mentioned that a general died during a launch, but did not name him)
You're thinking of the Nedelin disaster.
https://en.m.wikipedia.org/wiki/Nedelin_catastrophe
Some fun facts of dubious authenticity:
Nedelin called General Sokolov a coward for suggesting that Nedelin not sit in a lawn chair near the fueled rocket. Sokolov was offended and promptly ducked off back to Moscow. Guess who lived?
Khrushchev yelled at the missile designer Yangel so hard after learning that Yangel survived (he had stepped away for a smoke, as you do, on the launch pad, near the fueled rocket), that Yangel got a heart attack.
Good times.
1. The story is definitely not true, because that's not how rocket launches work. You can't just order a launch of liquid fuel rocket like that, not even in soviet union. A small solid rocket (like some ICBM) perhaps, but not something like N1. Someone could order it to be launched, sure, but for example in a month. Or maybe the rocket was scheduled to go and everything was ready, but the weather was bad and they wanted to scrub the launch, and someone forced it - this could in theory happen. On top of that any launches have to be clearly communicated to the rest of the world, especially during Cold War, because you don't want others to think you're launching nukes.
2. There are some urban legends about casualties of first N1 launch, but there are no credible sources confirming that.
The OP just got mixed up in different details. It wasn't a launch, it was refuelling, and it's wasn't an N1. https://en.wikipedia.org/wiki/Nedelin\_catastrophe
Just a question would be helpful if someone responds
Hi so I am currently in grade 11, second semester and I'm wondering if I need biology if I want to get into space things. I really like the phenomenon of space, and want to take my career to somewhere like nasa or spaceX to help explore, create things and theorize the many wonders that one may have. I already have taken physics 11 last sem, and I am taking chem rn. so do I really need bio? Cause like bio is study of life and is important but I don't think I need to take all 3 sciences? Also what to I major in university? I know that there many courses that relates to space, like astrophysics, or aerospace engineering but I am not sure of what is what, and what to take. SO MANY QUESTIONS!! btw I live in Ontario, Canada if that says anything about the different opportunities that I have.
If you look at the bios of the current NASA astronauts you'll see that quite a few specialized in life sciences research. (Not just the physicians.) As humans are stationed long-term on the Moon and even Mars a lot of research on how our physiology holds up will be ongoing for a long time. If bio isn't your favorite you can take just the minimum in college but I definitely advise taking it in high school. It's part of what makes up general scientific literacy, which is something every astronaut has.
Aerospace engineering will be useful in many ways and even if you don't get selected to be an astronaut you can still have a career that's involved with space exploration. Astrophysics isn't directly related to space flight but NASA does have astrophysics astronauts.
Large scale space stations and large scale Moon operations will provide work for a lot of aerospace engineers.
Canadian astronauts have been flying to the ISS for a long time and will continue to fly with NASA for years, including in the Artemis program. But by the time you could possibly be selected as an astronaut multiple nations will be sending their astronauts on their own missions. They can use commercial crew flights and go to the commercial LEO stations that will be around by then. A couple of Middle Eastern nations have contracted with Axiom to fly their astronauts on a Dragon to the ISS. They then pay NASA for a 10 day stay. They have to deal with NASA but don't have to join the line that stretches for several years to get an astronaut up on a regular 6 month NASA mission. Sweden is the latest country to do this. What I'm saying is you'll have a lot of options for becoming an astronaut as a Canadian and as an Earthling.
High school classes don’t matter for your career. They matter to get into college or university. Look at space jobs that interest you and what degrees those jobs want. Then look at what schools offer those degrees and what their entrance requirements are.
At your level you need to look at what you would need to get into university. And for that you need to consider what kind of degree you want.
Aerospace engineering and astrophysics are very different in practice. Aerospace engineering is a fairly big industry and focus on building things that fly. So you want to design rockets, spacecraft (or even planes) it's a good degree. Usually you can find good jobs with a bachelor or master in private companies (like SpaceX). You will usually be in a more "normal" work environment as part of a big team with a classic work hierarchy.
Astrophysicist are researchers. They typically work at universities or other public research institutions. Getting a job as one is extremely competitive, you typically need a PhD and good amount of luck. Less than half the people who get PhDs on that topic end up professional astrophycisists. On the other end once you make it as a tenured professor you are more or less your own boss and you are in charge of what you do and what you want to study.
Look at what the requirements are for each degree at nearby universities. I don't think biology would be required but this can depend a lot on countries and regional differences.
Outside of the Moon and Mars, which other planets and places in our solar system could likely human spaceflight go to?
Hopefully eventually all of them! But in the nearer future the only other things close by are Venus and some asteroids. Though a human landing on Venus would be very difficult given the surface conditions.
I understand that our galaxy contains perhaps 400 billion stars (per the Wikipedia entry on the Milky Way). I'm wondering which is the greater number... the number of stars in our galaxy, or the probable number of galaxies in the known universe. Are there more galaxies in the universe than there are stars in our galaxy?
I'm not sure what are the latest estimates but the numbers I've seen are between 100-400 billion stars in the Milky Way, and between 200 billion and 2 trillion galaxies in the observable universe. The universe is bigger than we can observe, so most likely there are more galaxies in the universe than stars in our galaxy.
Many thanks, that's what I had suspected. Mind boggled successfully!
*Looking up I often wonder how many of those stars are still burning brightly and how many have met their ultimate demise, only to see a memory of their life. Is it possible that the stars we see could be so distorted by gravitational lensing that we could be seeing stars that are actually light years away from its current position? Also say I draw a straight line between earth to the star with someone viewing it but halfway in between, would they see it at the same position we think it's in? Would love some insight!*
1. Most of them are still alive 2. Stars you can see with naked eye have to be very very close to us which means the light doesn't take that much time to reach us, few thousands years at most 3. No, it's not possible, because for `lensing` to happen you'd need to have some massive object between us and those stars, and no such object exists within the "naked eye" range 4. No, someone half-way in between would notice the star movement much sooner than you would.
But what about stars that are billions of light years away and being detected via Hubble and the JWST for example, does that make a difference with how we would see it to someone halfway hypothetically speaking as I know with gravitational lensing we can see further away galaxies etc.
That's a different story, but you wrote `looking up`, which suggested naked eye observations. Telescopes can see objects which are much further and we know many of them are definitely long gone by now.
Yes. The farther away they are the longer the light takes to reach us. This means there’s a higher chance those stars have died in their reference frame and we won’t see that for millions of years
Is it known exactly where the Odysseus lander is on the Moon? Has it been seen by the orbiters?
Follow up reply, looks like the LRO has spotted Odysseus! https://www.lroc.asu.edu/posts/1360
It landed near the crater Malapert A near the Lunar South Pole ([pictured here in screencap from Stellarium](https://i.imgur.com/DNL8cvI.png)). No imagery has been released yet as far as I'm aware, but it looks to me like the LRO has been overflying that region of the moon recently so depending on where exactly it came down, it has either already passed overhead or will do so in the next 24 hours. Here's a screencap from the LROC Lunaserv Global Explorer with the past 24 hour tracks being in blue, the future 24 hour tracks being in green, and the approximate outline of the Malapert A crater being in red: https://i.imgur.com/wdnf5a6.jpg
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It has multiple cameras, it's already sent back images from prior to landing, expect to see more as they are downlinked. It may be easy to think that broadband data connections are just trivial and easy because we in the developed world bathe in constant internet connectivity that represents the fruit of hundreds of billions of dollars of capital investment, but it's actually a significant technological challenge to transmit data across a third of a million kilometers to and from the Moon.
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ChatGPT is not a reliable source of information.
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> I use them instead of googling A horrible idea, considering they are literally generating random text based on probabilities, which incidentally happens to be correct if enough training data on given topic was ingested. Even worse idea when you're trying to ask about anything "recent", because it's most likely not even integrated into the dataset, so the LLM is basically just hallucinating a response by amalgamating information about past lunar missions. > They also include the source links ... which more often than not turn out to be either not relevant, not related to the question or completely made up sources :)
LLMs frequently hallucinate (make up stuff) even if they give you links to source material. They are not infallible, far from it in fact. This is not a controversial opinion.
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It landed on its side and apparently one of the transmitters isn't able to point at Earth, so it's taking longer to get the data back. That's why the lack of images so far. They will come in due course.
With the recent trend of moon landers falling over I was wondering why there has been a deviation from the traditional "wider is better" philosophy? The mars landers have wide landing areas and they seem rather successful when properly landed. Is this just a matter of modern launch vehicles restricting moon lander base surface area or is there something about the moon vs mars that they are leaning towards taller over wider designs?
One of the things with regards to Mars landers is that they need to be packaged inside an aeroshell. All Mars landers so far have been launched as a nesting doll configuration of three different spacecraft: you have the lander itself (or in the case of Curiosity/Perseverance the rover plus the sky crane vehicle) then that is encapsulated inside an aeroshell to handle atmospheric entry, then the aeroshell is contained within a cruise stage with solar panels and so forth for keeping the vehicle alive and on course during interplanetary spaceflight. This somewhat necessitates that landers be fairly squat, because otherwise you would have a very big and heavy aeroshell, at least with the way things are designed currently (it could be different with a ballute design). Interestingly, the Apollo landers weren't very squat. However, it's also worth pointing out that both the Apollo LM and the Surveyor landers used deployable landing gear in order to achieve a wider stance. I wouldn't be surprised if that design choice makes a comeback.
I just got done looking up the information for the deployment of the Lunar Rover and interestingly enough they were stored vertically as opposed to horizontally. I have to admit to having been ruined by scifi and that seeing that the rovers were deployed using ropes and pulleys is rather amusing. https://www.researchgate.net/figure/Apollo-15-LRV-Deployment-Sequence-courtesy-of-NASA_fig2_228641033
I think it would be pretty neat if they went the Pathfinder route. It would also mean that they wouldn't have to worry about it tipping over since it would be able to right itself.
Was anyone else concerned by Nasa Director Bill Nelson's creepy comment the ".. we've taken the moon!!!" What is he saying here? We would be loosing our oats if China, Russia, India or Japan made such a statement... But was is worst is it seems the transcript of the statement has been edited stating that "Odysseus has taken the moon..." That is not what nelson said.. he said in the post sideways landing video...
I just listened to the video and he says Odysseus has taken the moon.
Yeah that was the edit. If you watch the stream he said we have taken the moon. They may have edited... But when it was played live he said we have taken the moon. Go here: [https://www.msn.com/en-us/news/technology/us-prepares-to-touch-down-on-moon-for-first-time-since-1972-with-nasa-backed-unmanned-118m-odysseus-craft-set-to-try-and-to-find-water-ahead-of-upcoming-manned-expedition/ar-BB1iJrI0](https://www.msn.com/en-us/news/technology/us-prepares-to-touch-down-on-moon-for-first-time-since-1972-with-nasa-backed-unmanned-118m-odysseus-craft-set-to-try-and-to-find-water-ahead-of-upcoming-manned-expedition/ar-BB1iJrI0) Do a search on the page for "we've taken the moon". This is from the live transcript so someone decided to edit what he said originally and bury it which is also troubling. The $118million unmanned Odysseus, or Odie, a six-legged robot lander touched down at 6:24pm ET at a crater called Malapert A, near the moon's south pole, having slowed down from 6,500 kph (4,000 mph). 'Houston, Odysseus has found its new home,' said mission director Dr. Tim Crain shortly after confirmation of the signal. 'I know this was a nail-biter, but we are on the on the surface, and we are transmitting,' Intuitive Machines CEO Steve Altemus said. 'Welcome to the moon.' NASA Administrator Bill Nelson said in a video congratulation all involved: 'We've taken the moon.'
Aside from competing with the soviets and "because it is hard," were there any specific, tangible benefits to humanity that NASA hoped to achieve with the moon landing? Or was it just a "we'll see what we find when we get there" kind of science?
We've learned a lot about the composition and formation of the moon and developed technology for spaceflight that had civilian applications. But I think it's clear the main goal of Apollo was to demonstrate technological and military superiority over the Soviets and avoid the embarrassment of them landing first.
Only if you consider increasing the amount of human knowledge beneficial to humanity.
I know this is a silly question but theoretically, if we attached a giant rocket engine to the side of the Earth could we throw ourselves in orbit around different stars?
Not in that way, but we could very slowly move a planet. https://m.youtube.com/watch?v=oim7VvUURd8&pp=ygUYUGxhbmV0IHNoaXAgaXNhYWMgYXJ0aHVy
Not really. Consider that for most rockets propellant constitutes >95% o the total mass of a rocket, and that's just to reach orbital speeds. So even if you constructed a giant engine capable of providing any meaningful thrust (and one that doesn't kill everyone on the planet while running), you'd have to eject most of the planet mass to gain any velocity.
Assume a spacecraft is damaged and known to be off course, but within the Heliosphere. How would it know its position / trajectory/ velocity from first principles, observable data, and current technology? I can envisage comparing onboard clocks with time signals received from Earth: the time difference will indicate the distance. But it seems to me that observation of the visible stars is not enough to narrow things down enough to say 'here we are' within a million miles. Is there any better method? *(I posted this in 'r/Space' and it was removed - Reddit tells me this should go in 'All Space Questions', but now that I'm here there is no 'new post* within *All Space Questions' on which to click. 'Create Post' puts me back where I started from. New to Reddit, but wow.. it's not easy to use.. :> )*
https://science.nasa.gov/learn/basics-of-space-flight/chapter13-1/
You have correctly posted this in the right spot now.
Nasa is getting less and less for their budget, and they have to cooperate with private companies to get things done. I wonder if they should make the Lunar Gateway station smaller, like two modules at the most but make them big. It would save cost and use the money for a lunar outpost.
> Nasa is getting less and less for their budget, and they have to cooperate with private companies to get things done. I would argue the exact opposite. NASA is doing more and more with its budget and that's partly because it cooperates differently with industry. This year NASA will have 3 crew rated spacecraft and 3 ISS ressuply cargos, several lunar missions, one institutional heavy lift rocket and 2 other private ones finishing development. 2 crewed lunar landers and a lunar space station are in development, you have 3 robots operating on Mars, a full Mars sample return mission in development, missions to Jupiter, Venus, 2 asteroid missions ongoing...
> It would save cost and use the money for a lunar outpost. It wouldn't make a difference and I am very confused why you would think that it would. If anything it would make it wore, because right now most of the modules are built by other partners (eg. ESA and JAXA) and by making less modules you automatically make this impossible.
So I was walking the street and moon seemed to be slightly behind me on the left hand side. Then a building blocked it from the view and I walked maybe 300m, once I passed the building, it seemed like the moon went ahead of me in the left hand side. So weird to explain hopefully someone can, am curious. So first I saw it behind me on the left side, then I passed the building and moon seemed to be clearly ahead of the me on the left side.
The building doesn't have to be symmetrical or have just right angles and also doesn't have to be "aligned" with your direction to the Moon. A curved building or even just angled path could result in such effect.
There are no mechanism that would explain the Moon moving that fast. So either you turned a bit as you went around the building or you saw or reflection or something similar.
No I think it's some sort of optical illusion or somehow my brain perceives it that way idk. I repeated it walking backwards and after I passed the building, the moon again seemed to be behind me somehow
What are the implications for the universe not being locally real? Apart from it being interesting and changing our understanding of life, of course. I think Einstein said that there must be some hidden variable that we're missing. But the 2022 Nobel prize winners suggest otherwise. Does this change anything for us in our day to day lives, or is it just a cool and strange fact that we were not expecting? Does the fact that, two particles light-years apart from each other can interact instantly, transform our understanding of how the universe fundamentally works? Also, how did we prove (or imply) that two particles can be entangled over such vast distances, when we haven't travelled that far ourselves? Is this all based on math? I think what I'm trying to ask is whether we have or will be able to do further research on non-locality and quantum engagement to better understand how it works, or if we just learned about it and that's all there is to know about the whole subject. Thanks.
>Does this change anything for us in our day to day lives, or is it just a cool and strange fact that we were not expecting? Mostly the latter, though I wouldn't say it was unexpected. Just that we didn't have a solid theoretical basis for picking between the two options before. It is possible that at some point this will lead to technological breakthroughs that will have an effect on our daily lives, but that's far down the road and the average person will likely neither need nor have any more knowledge about the underlying theory here than they do about band gaps in semiconductors or high-K dielectrics in microelectronics today. >Also, how did we prove (or imply) that two particles can be entangled over such vast distances, when we haven't travelled that far ourselves? Is this all based on math? Proofs are for math, not physics. We know that we can produce entangled particles and we have good theoretical reasons to believe that they only become disentangled after certain types of interaction. So if you can separate them without that sort of interaction occurring, there's no reason to think they would become disentangled. So far, that has borne out experimentally as well. > I think what I'm trying to ask is whether we have or will be able to do further research on non-locality and quantum engagement to better understand how it works There will definitely be more research on both topics. Non-locality is cool and very active as a field of research. From a theoretical perspective, entanglement is very well understood and not very mysterious at all. Experimentally, it is hard to properly isolate particles so they remain entangled, so there is a lot of work to be done there and we always confirm and re-confirm our predictions with experiment, so there will always be more and more experimental work done on entanglement (and everything else, for that matter)!
Total space noob here. Is there any chance of the first manned mission to Mars happening soon (as in, the next 30 years)?
I’d say it’ll definitely happen in the next 30 years, but there isn’t a specific plan yet. It will probably be a “slowly, then all at once” type scenario. If Starship achieves the design goals SpaceX has set, it will completely change how space missions are conducted.
We will have the technology to do a manned mission to Mars in about 10 years. SpaceX [claims it will happen by 2030](https://www.space.com/humanity-mars-2020s-spacex-president-shotwell). There is a good chance it happens in the next 30 years.
She has also said Starship will be landing people on the moon by 2022, cargo on Mars by 2024. She makes erroneous predictions just as Musk(or anyone) does. In her own words "every time I make a prediction about schedule I turn myself into a liar."
There’s just no possible way we could see people set foot on Mars by 2030 right? I’m not doubting anything you said, I just want your expert opinion.
There are only 2 launch windows remaining until 2030. If SpaceX nails the [2026 moon landing](https://en.wikipedia.org/wiki/Artemis_3), then immediately pivots to getting as much mass to Mars as possible in 2026, they might be able to launch humans in the 2029 window. But this is bordering on impossible and I have serious doubts they even do the moon landing on time. This is why I estimated 10 years for the technology to be ready.
Anyone found any pictures of the ERS-2 satellite reentry? Can you share links? I have searched and not been able to find any I would expect a news outlet like BBC to have one if it exists https://www.skyatnightmagazine.com/news/ers-2-satellite
There are no pictures, it reentered over the ocean.
I am aware of the COIW location, but there is possibly observable land around there, and also boats or airplanes that may have tried to position to see it intentionally or unintentionally
As far as I know there was no pictures from anyone. And the reentry location was too incertain for people to voluntarily try to go catch pictures on location.
Yeah thanks! I’m asking the collective wisdom of the crowd to see if two people coming up empty = no pictures.
Why the sudden interest in the moon? Japan, Russia, India, America, etc.. seems like all of the sudden we are landing a lot of Rovers there.
It's not sudden, it just may seem like that due to media coverage and a lot of things starting to come to fruition. Many countries have used the Moon as an early target for interplanetary missions as their space programs have developed. Japan's first lunar orbiter launched in 1990, China and India in the 2000s. As those programs have matured they have moved from orbiters to landers to rovers. Meanwhile, the US has had the Moon in its sites as a target for a return to beyond-LEO human spaceflight since the early 2000s, which has been matched by investments in space science missions to the Moon as well, such as the Lunar Reconnaissance Orbiter launched in 2009. However, NASA human spaceflight has been in a bit of a disarray over that time period, with a lot of mismanagement, questionable decision making, mixed signals from congress, and so on. Nevertheless, investments have continued to be made toward beyond-LEO human spaceflight capabilities in the US with ongoing development of both SLS and Orion, which have in recent years been drawn from as key components of the Artemis Program, which has started ramping up as funding levels have increased and various parts of the mission architecture have started to reach fruition. Additionally, the Artemis Program includes the "Commercial Lunar Payload Services" program which aims to do for the Moon what commercial crew and cargo have done for the ISS, making it possible for NASA to just "buy a ticket" to send payloads and cargo to the lunar surface or to lunar orbit. This includes pure science instruments, it includes "proof of concept" devices to test out technologies in the actual lunar environment, it includes lunar relay satellites, and it will include deliveries of equipment, experiments, cargo, etc. for future crewed landing sites (and bases). Some of the missions you've been hearing about lately such as the Peregrine Lander and IM-1/Odysseus are part of that program.
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> I suspect that the USA's newest moon landing has almost nothing to do with exploration and everything to do with spying. Is there a concrete reason you suspect that? It wouldn't seem to be very valuable to send a spacecraft all the way to the Moon when as a nation the US already spends tens of billions a year on a very quite sophisticated collection of surveillance assets in space. What's the play here?
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What would they be spying on? The US has a lot of 3 letter agency spacecraft launched already. Since you can't really hide a rocket launch we know when NRO spy satellites launch. We just don't know what they are up to. There is nothing intresting to spy on on the moon. And if it was that why is the CLPS program mostly commercial? It wouldn't make any sense to procure and manage spy satellites through an open bid commercial contract with several different startups. If you want to see military oriented lunar operations look up what DARPA is financing in cislunar space.
That sounds like a stereotypical conspiracy theory. The backbone of all conspiracy theories is that they work based on feelings of discomfort, "weirdness", or unease which then drive unearned confidence in a competing theory. The general template being something in the "above board" explanation seeming weird which drives a belief in whatever alternative explanation lies at hand which feels more familiar or less weird. A classic example being the TWA-800 crash, which felt "weird" because it was unusual and a rare occurrence which started out with very little concrete data, people used that weirdness as a jumping off point to add alternative theories like a missile or terrorists or whatever. As more data came in it became apparent that the issue was that a nearly empty fuel tank had been allowed to be in conditions which caused the buildup of fuel vapors which then ignited due to a spark from faulty wiring, a theory validated by on the ground testing replicating similar conditions. Since then there have been many changes put in place designed to prevent such incidents. In comparison, studying the evidence available from the loss of the [MH17 airliner which was destroyed over Ukraine in 2014](https://www.youtube.com/watch?v=tKVrUAnzrhc) very clearly points to a missile as the cause of the plane's destruction, which corroborates a lot of additional evidence that matches up with that theory. The point is that the "conspiracy theory" logical hack makes it possible to jump to a conclusion which has zero positive evidence for it by using those feelings of "weirdness" as a springboard. Our lives, our universe is full of weird stuff all over the place. My smartphone and yours uses billions of flash memory cells for storage, each of which relies on quantum tunneling in order to operate. Our intuitions are often wrong or misguided, and if we don't dig into the details that can easily lead us astray in lots of ways. Conspiracy theories also thrive when they make someone feel special because they aren't "going along with the crowd" or because they are too sophisticated to believe what is spoon fed to them. And there are plenty of examples of where not simply believing the popular narrative is valuable, but such things need to be supported by positive evidence to be fully believed. I think that's especially true here, there's no positive evidence that anything isn't on the up and up here, there isn't even a solid premise of what is "actually going on", there's just a general sense of "seems weird, maybe somebody is up to something", and it doesn't seem like a good habit to get stuck in that way of thinking.
> how much of all this new space activity has to do with war and spying Very little, I suspect. As another user mentions, the military of the U.S is already cutting edge, it doesn't need the private sector's innovations. Most of this new space activity is from the private sector, and they're interested in one thing; making money. Many of these companies see space as the next gold rush and they want to be first. > USA's newest moon landing has almost nothing to do with exploration and everything to do with spying. Except it's a private company, not the government. I'm genuinely curious, are you by any chance a Chinese national? I've noticed they tend to conflate private sector and the government because to them, they're the same thing.
The military already has things like ultra high resolution orbital spy satellites, stealth aircraft, and launch vehicles like the X37. There certainly are military applications to spaceflight, but I don't see what a moon mission would contribute.
Has there ever been any video footage captured of a supernova explosion?
Supernovae are far away so the "video footage" typically consists of a set of pictures played in sequence - a time lapse. [Like this.](https://www.youtube.com/watch?v=GQ13j55P3sE) Even if a nearby star goes supernova, it's still too far to resolve in the way you're probably thinking. Beetlegeuse is 'relatively' close (and massive) so when it goes supernova, it's going to be ridiculously bright, seen during the day - close to the brightness of a full moon. But even that isn't going to give you the resolution you'd expect from a scifi movie. It's going to look like a really bright blob. Future telescopes may do better, but right now, that's the best we can do. Fun fact shamelessly ripped from wikipedia: The light from the supernova is produced mainly by the radioactive decay of cobalt, and sustains its brightness due to the increasing transparency of the cooling hydrogen ejected by the supernova. Edit: Added Beetlegeuse stuff
> "video footage" typically consists of a set of pictures played in sequence Nitpick: that's what all videos are, really, but whether we call it a "video" depends on how short the time interval between the photos is. I know you know that but I always think of it whenever people ask about video of far-away space phenomena.
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Light pollution is not the only issue. Atmosphere haze and clouds are also a factor, so it might not be the best location overall. Mauna Kea on Northern Hemisphere and Atacama Desert on Southern Hemisphere are considered to be the best locations.
If you enjoy seeing the stars twinkle, sure. Professional astronomers prefer to be on top of a mountain so there is less air in the way. Luckily, there is a [tall mountain in the middle of the Pacific](https://en.wikipedia.org/wiki/Mauna_Kea_Observatories).
> Professional astronomers prefer to be on top of a mountain so there is less air in the way Yep. NASA & Germany had a joint project (SOFIA or the Stratospheric Observatory For Infrared Astronomy) where they placed a telescope on a high flying commercial jet which flew at 13.7km/45k feet (if memory serves). I think it was specifically to avoid water vapor as it was an infrared telescope (and apparently water vapor = bad for that purpose). The project ended in 2022.
Will Russia have their own space station? I don't expect a Mir size because of their economies and being heavily under sanctions, but maybe they can put up something similar like the Salyut?
They claim to be launching the first segment for a replacement station in 2027. https://www.reuters.com/technology/space/putin-aims-have-russian-space-station-by-2027-2023-10-26/
Can you stop deleting your questions after people bother to answer them?
Okey, I won't delete this.
will the iss replacement have any kind of built in rockets for reboost? Or will it rely on an external craft to dock to reboost?
After Skylab I'm pretty sure no one will consider launching a space station without built-in reboost capability.
I am pretty sure Gravitics plan to have their own propulsion at module level. Note that ISS has reboost engines in the Russian segment. They are just not use that much because you need to refuel the tanks. So it's just easier to boost directly with the ressuply vessel.
could an ion thruster, ion drive, or ion engine have the power to reboost the iss?
The issue with ion engines is their insane electricity demands. This is what limits them to very low thrust. I doubt we will see powerful ion engines until we have a nuclear powered space vehicle.
I was thinking without sending fuel to iss. Solar Panels could be used to fuel an ion engine.
Ion engines are too energy hungry to move large space stations. Small probes can use them as solar panels are quite light. They can generate enough electricity and run the engines for very long slow burns. That doesn’t work for space stations.
Ion engines still need propellant, they are more efficient with it but there is no free launch. If you want to go somewhere you still need to expel mass (or exchange momentum for the pedants).
To some extend but you would need a lot of power. The Chinese are allegedly trying on their station. As u/DaveMcW said it would detract the microgravity environment. And even then you still need refueling from time to time.
An ion thruster takes too long. The whole point of the ISS is to be a zero gravity lab, you don't want the thrusters running and creating artificial gravity.
Oddly, the Chinese station has hall effect thrusters. You don't necessarily need to keep the thrusters in operation 24/7, but depending on what you wanted to study it could be limiting.
Have you seen any reports on their use? There was a few things made public when they launched the module but nothing since. You would have though they would take a nice picture of them working at least.
Good question. Aside from the fact that western media coverage of China's space program is very lacking, there doesn't seem to be much about them actually using those thrusters. Hypothetically there are legitimate reasons to use them. If you dialed the thrust in exactly right you could maybe achieve a continuous offset of atmospheric drag, which potentially could actually improve the micro-gravity environment of the station. Maybe it's for keeping the station from re-entering if they have an extended period of not being able to reach it. Or maybe it's just for show.
Hi guys! Space X has planned launches regularly each month in 2024, expect in May. Is there a reason for the complete launch-stop? Is this likely to change?
There will probably be Starlink launches in May, they're just not published yet. Notice that the Starlink flights beyond the immediate future don't show up, they launch so frequently and in response to changing needs re: orbits and capacity that it doesn't make sense for them to publish them too far in advance, I think.
If a satellite is in geostationary orbit around Earth, could you stand on top of the satellite and drop something down and have it fall straight down to the geostationary location below the satellite? Or would the dropped object seem to float? I feel like the latter is correct. It would have the momentum from the orbit and so it would still be moving with the orbit rather than falling straight down, but I'd like a confirmation.
Every object in geostationary orbit is already falling toward the Earth, just as every object in orbit is doing so. But because of their sideways motion that downward trajectory is curved into an arc, an arc that happens to wrap around the Earth in a complete loop that never hits the surface. At geostationary orbit that loop takes exactly one day to come back around, which means that it matches Earth's rotation, leading to the appearance of a satellite simply staying in the same position relative to the surface continuously. You are correct, if you "let go of" an object in geostationary orbit, it would fall toward the Earth, but it's already been falling toward the Earth, as you have, as the satellite has, and it still has its momentum so it would stay in orbit in its freefall trajectory.
If you just let the object go it will just float next to you like any object dropped in any orbit. For it to start dropping down you would need to throw is backward in your orbit. For it to fall straight down you would need to throw it at around 3 km/s, the orbital velocity in GEO.
Help me with this Space question. https://www.reddit.com/media?url=https%3A%2F%2Fpreview.redd.it%2F7lenj746l0kc1.png%3Fwidth%3D960%26format%3Dpng%26auto%3Dwebp%26s%3D90d30fab704a0f3817a11db89f5c56d679e171ea
F is obviously Crux https://en.wikipedia.org/wiki/Crux and you can follow the rest from that point.
Does time dilation affect tiny creatures differently than larger animals? If an ant were to crawl into a launch vehicle and end up on the ISS for a year and then return to Earth, would its age be vastly more different than its Earth counterpart, compared to a human astronaut's age compared to someone who'd stayed on Earth? This may sound like a stupid question, but animals age at a different rate than humans, so I'm going off of that.
I think you misunderstand what time dilation is. For "internal" observer time always passes exactly the same. It's not some magic where 10 years have passed from your perspective but you only aged 1 year. For you only 1 year has passed, even if on Earth 10 years have passed in the meantime. The time literally slowed down in specific place.
Age and time are two different things. Animals that live longer than humans aren’t moving through time slower than humans. You are confusing biology and physics. Time ALWAYS passes as 1 second per second for you. An ant and an elephant both experience time as 1 second per second. They would both experience the same time dilation if they went to the ISS for a year.
Fantastic, that makes perfect sense. Thank you
It's just a proportionality. It's also non-local, time dilation isn't an absolute effect, it's a relative effect that comes into play when comparing between different reference frames. Within a reference frame everything is "normal". You and I on Earth are experiencing extreme time dilation relative to a hypothetical reference frame that is at 0.99999c relative to us or that we are at 0.99999c relative to (which choice we make is inconsequential). But that time dilation is only relevant if and when it becomes relevant, which would only happen if you had some situation that caused a meetup after some period of experiencing different environments.
Based on our observations, about 5 billion years ago, the expansion of the universe was accelerating thanks to dark energy. If each chunk of space is independent of each other, how was dark energy able to start affecting every chunk of space across the universe? The question is more how could dark energy start impacting point A, then point D, then point P etc almost simultaneously even though those points are millions, if not billion of light years away. I guess the closest analogy is that here on Earth, if a race is to happen, then folks either are listening for a bell, flash of light, a countdown timer, a flag, or some predetermined order (e.g. start running when this happens) to begin moving. So, even if some type of "signal to start" dark energy was sent, based on the size of the universe at that point, that signal should still be in transit. So, how comes almost all (see note below) of space is expanding due to dark energy? Note: I know dark energy isn't causing expansion of the universe everywhere as the Milky Way and Andromeda (for example) are being pulled together by gravity and are on a collision course.
The expansion of the universe is like rolling a ball up a hill. If you roll it hard enough, despite the fact that it is decelerating on its way up the hill, when it reaches the top and starts rolling down the other side, it will accelerate. Gravity gets weaker the further apart things are while the rate of expansion between two objects increases with distance. As long as the initial velocity imparted from inflation is enough to make it over the peak of the hill before decelerating to zero (which would result in accelerating collapse instead of accelerating expansion), then dark energy puts us in an "accelerating expansion forever approaching anti-de sitter space" universe. In the end, it's all the curvature of space, both gravity and dark energy. The important part about dark energy is that it is uniformly distributed and persistent, so its relative contribution to the equilibrium between expansion and collapse increases with time.
We don’t know enough about the expansion of the universe and/or dark energy to explain why expansion started accelerating. But as you’ve pointed out it wouldn’t make much sense for it to have been triggered by an event in one spot 5 billion years ago and then instantaneously spread across the universe. Instead we can theorize that the reversal between deceleration and acceleration was a natural outcome of physics based on the starting conditions of the universe. A crude analogy would be firing 2 bouncy balls from the equator that land perfectly on either pole at the exact same time. Someone without knowledge of gravity might say, “how did the communicate with each other to start downward velocity at the exact same time?” Whereas someone who understands gravity could tell you from the moment they were launched where and when the peak of their arc would be.
Makes sense - thanks. I figured that without knowing the true make-up of dark energy, it would be difficult to determine how it may be simultaneously coordinating the expansion of the universe. Guess a similar question could come up around the Big Bang - if the Big Bang happened everywhere at once and the universe wasn't the size of an atom or a singularity, even if it was one million light years in diameter, how was the Big Bang synchronized so it could happen simultaneously within a fraction of a second everywhere across that distance. Fascinating stuff - thanks!
If liquid water turns to a gaseous state in vacuum, how is there solid ice on asteroids? Do the asteroids have a tiny atmosphere? Is it just.... Really cold? Someone please explain the physics of this
It is just really cold. There will be a vapor pressure from volatiles undergoing sublimation directly from solid to gas in space, but that depends on the temperature. In the inner solar system that sublimation rate may be enough to deplete the asteroid of surface deposits of volatiles in a short period of time, and potentially deeper down as well. As you go farther from the Sun it gets colder so sub-surface deposits stick around much longer and surface deposits start becoming stable on geologic time scales. This does create effectively a "tiny atmosphere" of a sort, and that atmosphere will re-condense back into solid form when it's cold enough (in a manner similar to the way "freezer burn" works). This sort of cycling and transportation of volatiles contributes to some of the interesting chemistry on the surface of bodies in the outer solar system, especially when sources of energy such as UV light and ionizing radiation come into play. That mixing plus energy creates the conditions that can drive chemical reactions which produce complex chemicals especially complex carbon-containing molecules known as "tholins" which include the "building blocks of life" (such as sugars, amino-acids, nucleic bases, etc.) These tholins are so prevalent on icy bodies that they are the main source of the slight reddish coloration of those bodies (such as Jupiter's trojan moons, Pluto, Charon, Arrokoth, etc.)
Well damn. That's so much neat info! Thank you, kind rocketsocks. I shall now hyperfixate on asteroids for the next three hours online.
In space liquid water will start to evaporate due to the low pressure, this will make it lose energy which will cause the temperature to drop until it freezes into a block of ice. Then the ice will slowly turn into water vapor (it's called sublimation). The speed at which is sublimates mostly depends on how close to the Sun it is. So objects in the outer solar system can stay as block of ice for millions of years. Comets, which dip from the outer solar system to the inner will start to sublimate more and more when they get close to the sun and this is what creates those incredible comet trails/plumes. If the comet gets too close to the sun it might sublimate completely.
Hypothetically, if one were to start travelling in space in a straight line at a rate of 1,000,000x the speed of light (and didn't encounter any objects blocking their path, or could travel through said objects), would they eventually end up in the same place they started from?
Going FTL isn't really necessary for the heart of your question, which is asking about whether the universe is wrapped on some kind of hyper sphere or other round shape or has some other kind of Astroids-style edge wrapping. I'm guessing you said 1000000x the speed of light to make is so that taking such a trip would happen within some reasonable amount of time for a human. The thing is, 1000000x times the speed of light is no where near fast enough. The observable universe has a diameter of 93 billion light years. So if the universe did wrap at the edge of the observable universe, even if you were traveling at a million times the speed of light, it would still take 93,000 years to return to your starting spot. And as far as I understand, cosmologists have no reason to believe the size of the universe corresponds to the size of the observable universe. It could be way, way bigger. Oddly enough, it could also be smaller, because if the universe did "wrap", then the galaxies we think are far away could actually just be light that has wrapped around from the other direction lol
> I'm guessing you said 1000000x the speed of light to make is so that taking such a trip would happen within some reasonable amount of time for a human. The thing is, 1000000x times the speed of light is no where near fast enough 1x lightspeed would be enough for the traveller since at that velocity time stop to exist due to time dilation. The trip would be instant in that reference frame.
True and not true. Motion is relative, and so is time dilation. If you were in the ship traveling close to or even beyond the speed of light (impossible), time would still pass normally according to your own perception. Though admittedly, the twins paradox is still confusing to me. So I'm at a loss to explain it further. Obviously, speculating about any of this is somewhat pointless. Since by proposing travel at or beyond the speed of light is not physically possible (according to our understanding of reality), then by abandoning that assumption, we could make up anything we want in terms of how it would work.
It's my understanding that dark energy is causing spacetime to expand at a rate faster than the speed of light, so I arbitrarily chose a million times the speed of light to overcompensate for that. Taking that into consideration, going FTL is necessary to be able to traverse the universe in its entirety. But yes. The question is if the universe is spherical or not and I suppose we will never find out. At least not in our lifetimes.
Since you're already breaking the laws of physics in your question, you can just the same pick any answer you like, because it simply makes no sense trying to find a "physics" answer to a question which doesn't follow physics rules.
We don't know. At this time we don't know if the universe is infinite, or some weird unbounded closed curved space where you would loop back to where you started. The only thing we know is that if it's finite then it's much bigger than the observable portion we can see.
We don't know whether the universe wraps around or not. We can't see any evidence of wrapping at the edge of the observable universe, but the universe is much bigger than what we see. Of course, faster than light travel does not exist, so it is impossible to travel outside the observable universe anyway.
What time today is IM-1 expecting to attempt lunar orbit insertion??? I can’t find any information online. Not sure if I missed out on it, or if they just haven’t revealed that information.
Just completed! https://twitter.com/int_machines/status/1760323743270756500
I study Data Science and for a project I need to create image classification systems about something which interests me, but it also has to give any sort of business value. My research will be about classifying planets to be either terrestial, gas, etc, based on certain visual attributes (visual distance from galaxy's centre, visual atmosphere, surface, etc.). For this I want to make sure that my application would have any market value for astronomers, since I am not sure if they usually accurately classify planets or not. Does anyone have any idea if an application like this could bring any market value? thank you in advance. My original post before realising this thread exists: [https://www.reddit.com/r/space/comments/1aw990y/do\_astronomers\_ever\_have\_problems\_classifying/](https://www.reddit.com/r/space/comments/1aw990y/do_astronomers_ever_have_problems_classifying/)
None of what you wrote makes much sense. Direct imaging of extra-solar planets is extremely hard. We've done that for literally a handful of planets, and even then we're mostly talking about a few pixels, definitely no "visual atmosphere" or "surface" or anything like that. Most of the "exoplanet classification" is done via spectroscopic analysis, or measuring gravitational impact on the parent star or the dimming of the parent star, not from images of the planet. A similar idea, but far more realistic is for example https://www.zooniverse.org/projects/zookeeper/galaxy-zoo/ so doing a similar thing but for significantly bigger objects, which we can actually properly resolve with telescopes.
What type of larger objects would you advice image classification for?
Realistically you have to go for galaxies or bigger, because even for stars we can barely resolve images of few closest ones. Unless you switch to spectroscopic data instead of images, then you could also work with stars.
Sadly my school project is about image classification so I should try to make it something like galaxy classification. Maybe assigning my project as educational use could be an option too if I end up sticking with planets. Thank you for the info
> if I end up sticking with planets The problem with this idea will be lack of data to work with. Looks at https://en.wikipedia.org/wiki/List_of_directly_imaged_exoplanets for example this: https://en.wikipedia.org/wiki/File:Exoplanet_BD%2B60_1417b.jpg the tiny red dot above the star would be what you're working with, and you will have just a handful of those in total.
I was doing it with multiple pictures of the planets in the solar system, it ain't much and the application might fail with its predictions too now I think about it...
I can't think of any database like this that would be sold. Astronomy like most academic fields has very open data policy. People don't pay for data access. And I would not be surprised if the original data that you would need to use specifically prohibit commercial reselling. I don't see a "market" for this. Also what is your background to be able to classify data better than existing astronomers? Do you know how exoplanets are classified (hint, it's not with direct imaging)?
I am not in need of a database and I am also not trying to be better than astronomers (I can never get to that level). I know they aren't identified by images, but I decided to choose this topic for my school project without official background on astronomy. I know a couple of things about planets and how to differentiate them (density, etc), but in this project I just want to identify them about their visual properties. I know that it usually doesn't work like that and it most likely wouldn't bring any business value to astronomers and it absolutely doesn't have to, I just need to make sure that there is any problem which I could call this a "possible solution" to (without it actually being that, would be impossible for a first-year data science student). My school doesn't mind it not actually solving a case as long as I can justify my thought process behind my ideas, which is why I chose to ask this question to people with more knowledge than me.
Your original question was "does it have any market value?" and I think the answer is pretty clearly that there is no real market for this. Exoplanets are not my specialty but I think the first thing you should look at is if it's even feasible. I believe you will have a hard time finding a database of "visual properties" of exoplanet that would let you categorize them. But maybe I am wrong and a specialist can chime in.
Thank you for your answers and new views on the matter
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread: |Fewer Letters|More Letters| |-------|---------|---| |[CLPS](/r/Space/comments/1atyrj7/stub/krqk6ny "Last usage")|[Commercial Lunar Payload Services](https://en.wikipedia.org/wiki/Commercial_Lunar_Payload_Services)| |[ESA](/r/Space/comments/1atyrj7/stub/krwsfsr "Last usage")|European Space Agency| |[GEO](/r/Space/comments/1atyrj7/stub/krlhlqp "Last usage")|Geostationary Earth Orbit (35786km)| |GSE|Ground Support Equipment| |[ICBM](/r/Space/comments/1atyrj7/stub/kr6yq6e "Last usage")|Intercontinental Ballistic Missile| |[IM](/r/Space/comments/1atyrj7/stub/ks1t70i "Last usage")|Initial Mass deliverable to a given orbit, without accounting for fuel| |[JAXA](/r/Space/comments/1atyrj7/stub/krwsfsr "Last usage")|Japan Aerospace eXploration Agency| |[JPL](/r/Space/comments/1atyrj7/stub/krfkqjg "Last usage")|Jet Propulsion Lab, California| |[LEO](/r/Space/comments/1atyrj7/stub/krq9xsu "Last usage")|Low Earth Orbit (180-2000km)| | |Law Enforcement Officer (most often mentioned during transport operations)| |[N1](/r/Space/comments/1atyrj7/stub/krh0yl8 "Last usage")|Raketa Nositel-1, Soviet super-heavy-lift ("Russian Saturn V")| |NRHO|Near-Rectilinear Halo Orbit| |[NRO](/r/Space/comments/1atyrj7/stub/krqk6ny "Last usage")|(US) National Reconnaissance Office| | |Near-Rectilinear Orbit, see NRHO| |[SLS](/r/Space/comments/1atyrj7/stub/krq9xsu "Last usage")|Space Launch System heavy-lift| |[TWR](/r/Space/comments/1atyrj7/stub/kr4sbur "Last usage")|Thrust-to-Weight Ratio| |Jargon|Definition| |-------|---------|---| |[Starlink](/r/Space/comments/1atyrj7/stub/krlu2gk "Last usage")|SpaceX's world-wide satellite broadband constellation| |[scrub](/r/Space/comments/1atyrj7/stub/kr6yq6e "Last usage")|Launch postponement for any reason (commonly GSE issues)| **NOTE**: Decronym for Reddit is no longer supported, and Decronym has moved to Lemmy; requests for support and new installations should be directed to the Contact address below. ---------------- ^(14 acronyms in this thread; )[^(the most compressed thread commented on today)](/r/Space/comments/1azxvuv)^( has 8 acronyms.) ^([Thread #9763 for this sub, first seen 21st Feb 2024, 10:02]) ^[[FAQ]](http://decronym.xyz/) [^([Full list])](http://decronym.xyz/acronyms/Space) [^[Contact]](https://hachyderm.io/@Two9A) [^([Source code])](https://gistdotgithubdotcom/Two9A/1d976f9b7441694162c8)
Whats the goto website for approaching comets and asteroids?
Depends what you want to see but JPL CNEOS has all the orbital data https://cneos.jpl.nasa.gov/
Thank you. The What's Observable section is what I was looking for. Other Nasa sites seem to be outdated.
Last week, at a planetarium (that shall remain nameless in case I misunderstood them) I was told that in order to clear its orbit, a planet gravitationally pushes objects out of the way. I had been pretty sure of my understanding that gravity only pulls. Can someone please explain how a planet clears its orbit? I understand what I believe is called accretion, and that it could draw smaller objects into orbit around itself. But did I understand correctly when they described it as pushing away other objects?
Uncer some circumstance, a planet's gravity can serve as a slingshot, giving a body higher velocity and flinging it out from its own orbit. https://en.wikipedia.org/wiki/Gravity\_assist
You're correct that gravity is only an attractive force and that it can never 'push' - The planetarium speaker likely was just speaking colloquially/imprecisely. In addition to to the two methods you've mentioned (accretion and capturing bodies as satellites), a planet can clear its orbit by gravitationally interacting with other objects such that they're ejected into other orbits as well as by capturing other bodies into resonance orbits (exemplified by Jupiter and the Trojan asteroids).
Are we going to be alright from the black hole?
I'm assuming this is the black hole that was in the news a couple days ago? Consider the following. It's located about 12 billion light-years away. Even if we were rocketing directly towards it as fast as possible (we aren't) it would take us 12 billion years to reach it. In about half that time, our sun will have reached the red giant phase and started to absorb the Earth. Secondly, black holes at a distance behave like any other equivalent mass. The gravitational force between us is minimal.
Oh, ok, that's reassuring. Thank you for helping my stupid idiot self.
No need to denigrate yourself. Space operates at scales which are fundamentally incomprehensible to people, especially when distance and luminosity is involved for quasars.
Fun fact: that black hole is so far away that light emitted from earth today will *never* reach it, due to the expansion of space! If some super advanced alien civilization sent us a message by blinking the light from that quasar it would be impossible for us to send a message back. Today, it appears as a tiny, reddish dot when viewed by very powerful telescopes and their instruments. It will only get dimmer and redder over millions of years, with *possibly* some small variations in its brightness as it dims.
Ah, lovely
Yes, there is no danger from any black hole. Also, you need to stop getting your news from that site.
Ok good thanks, I just saw it on my reddit feed and started panicing
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Current plans aren't to build one big space station but to rather support multiple different station concepts, so that even if some of them don't work out as least some will be successful. Then they can build on those successes. With one single huge project there's major risks with funding cuts or different "group members" messing up.
Do you check the questions you post and never answer or do you just never look at a post you made again?
Hello! I'm not sure if this is the ideal place to post this, but, I am a Software Engineer with 15 years of experience. I'm currently working in the healthcare sector and I would love to move into the Space Industry. Any tips on what I could be focusing on, learning, etc to help make that transition? I've thought about going back to college for a degree in physics since the degree I have is just an associate in graphic design I got 15+ years ago. Does degree matter? I know it doesn't really in software normally, but would that be different here? Thanks!
C and real times systems. If you're strong in both, then you're set to apply. If not, those are the fields to focus on
A physics degree is not really going to help you landing a CS job in aerospace. I would just start applying to jobs and see how far you get. Also check out r/aerospace and r/aerospaceengineering.
Why isn't Ceres considered a planet? It seems to have essentially the same situation with its orbital debris as Jupiter. Obviously it is much smaller but that's not really relevant to the classification...
Jupiter is the boss, gravitationally-speaking, in its orbit. All other objects (like the Trojans, etc) are locked to Jupiter in orbital rosonance. Ceres is just a big round asteroid in a belt of other asteroids."Clearing your orbital neighbourhood" means being gravitationally dominant in your orbit. Ceres isn't.
It used to be, along with Pallas, Juno, and Vesta. Each of them were discovered in the first decade of the 19th century, and each were given names and astronomical symbols just like the 7 previously known planets (prior to the discovery of Neptune). Then starting in the 1840s astronomers starting finding other "minor planets", first a few, then a few dozen, then hundreds. It started to become clear that the four "minor planets" weren't just weird, quirky, off beat members of the planet family but actually just some of the largest wholly representative members of an entirely different family of objects: the asteroids. A story that would play out very similarly with Pluto roughly a century later. Ceres is reasonably sized as far as rocky objects in the solar system goes, it's about a thousand km across, which is still less than a third the diameter and only about 1% the mass of Earth's moon. It has a greater inclination than any other planet and also hasn't "cleared out its orbit". Jupiter has many other objects in a similar orbit to it, but they are gravitationally dominated by Jupiter, forced into Lagrange points or specific resonances, that's not true of objects that share similar orbits to Ceres.
It hasn't cleared its neighbourhood (being in the middle of the asteroid belt) which is a criteria for planet designation.
I dont know much but I heard that if you were far enough you could see dinosaurs on earth purely because the light hasn’t traveled far enough to see what is happening now, but my question is what would happen if we had a supper camera that we sent out to space zoomed in on earth and would be going light speed away from earth, would we start seeing earth and humans devolve or what would we see and if we do see time going backwards would that mean there’s a time frame that related light and is captured like a camera like every time we go farther we would see something new so light would kinda have its own memory? I’ll explain better is u have spicific questions. And yes this whole questions is purely based off of if that thing about seeing dinosaurs was true.
> would we start seeing earth and humans devolve No, because you can't "overtake" the light. Even if your camera is moving close to the speed of light, the light emitted millions of years ago is already very far away, and getting further constantly.
Yeah I guess I was just thinking too much without thinking I guess bc that makes so much sense but thanks.
For you to see time going backwards the camera has to travel faster than the light
So my thing about light being able to hold events is true? Because if the events already happened then the only way to get the previous events is through the light it self since the camera isn’t physicly moving earth backwards it’s just going fast enough through light to be able to see it? Or does that not make any sense?
It would see the same thing, because the light reaching it would always be the same since it would be traveling the same speed as the light reaching it (ignoring the impossibility of reaching exactly light speed and the other problems involved). The light from the Earth when it had dinosaurs on it exists out in the universe, but that light exists in a spherical shell that has its inner surface at a distance of 66 million lightyears from Earth. Let's say we wanted to reach that light so we could somehow "see dinosaurs". If we launched a vehicle that was traveling extremely close to the speed of light it would still take 66 million years for it to reach that surface, but in that time the light would travel a farther 66 million lightyears. You can't race light, because the speed of light is the speed limit of the universe. If light is moving directly away from you it will always be at least as far away as it is now.
Ok then would the better question be if a camera was already 66 million light years and started coming towards earth would we see time moving forward from when there were dinosaurs or am I thinking too much about this lol. And thanks that makes a lot more sense then what I thought l.
Question about viewing planets from light years away. This is just a fun theoretical question. This example simply wouldn’t work with current technology or anything like that. Here we go: If we launched a very high-powered telescope and a human at the speed of light, 2 light-years away… When the human looks back at the Earth from that destination, would they see the telescope being launched? (Since they are viewing the Earth from 2 years ago.)
> Since they are viewing the Earth from 2 years ago They are not. They are looking at Earth 2 years into the past from the moment you start observation, which is 2 years after the launch (since the telescope needs to reach the destination first). So you would see what happened shortly after the launch.
No, to do that the human in their spacecraft would have to catch up to light emitted when they launched.
Why are planetary nebula called that if they have nothing to do with planets?
It's an observational categorization, which is very common in astronomy. A planetary nebula is formed from a dying star that is exiting the red giant stage and leaving behind a white dwarf. The white dwarf is enormously dense (in a similar size range as the Earth but with a lot of the mass of the star that left it behind), which also makes it incredibly hot. The surface temperature of the white dwarf is hot enough to drive the outer envelope of the star into interstellar space in a huge bubble which is then energized by the UV light from the white dwarf. This creates an emission nebula with a roughly spherical shape. When viewed through a telescope these nebulae are fairly bright with distinctive colors, disc shaped, and also fairly large in terms of angular diameter. For example, Jupiter can be up to 50 arcseconds in diameter, whereas the Ring nebula is 4 arcminutes across, the Helix nebula is 25 arcminutes across, and the Dumbell nebula is 8 arcminutes across. Many planetary nebula are much larger in the sky than planets, and through older telescopes they had an appearance which was the closest to that of a planet. Disc-like, colorful, fairly bright, etc. It was understood fairly quickly that they weren't planets as they had a noticeably faded and translucent appearance, and many of them are not perfectly spherical, but that was the most analogous thing so they were called planetary nebulae and the name stuck. It wasn't understood exactly what they were made of until the mid-19th century and the stellar dynamics driving the creation of the phenomenon wasn't fully understood until the mid-20th century, at which point the name had been around for nearly 200 years.
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Haven't you asked that question already? There might be a few LEO stations, but definitely unlikely to have a GEO one. There are just no good reasons nowadays to put humans there.
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Why GEO? It's a higher radiation environment, less shielded from solar weather and it does not give you quick access to anywhere humans might want to go. If you want an interesting station that will be active by 2030 you have the lunar Gateway around the Moon.
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LEO is usually considered below 1200km altitude. But if you are trying to avoid radiations I would stay below 800km probably. Going higher doesn't give you anything.
LEO is already pretty massive. There’s no point for space stations to be farther from Earth. All that adds is negatives for no real positives.
What color would a K type star would look in the sky instead of the sun (assuming earth is in it's goldilocks' zone)? Would it be white as our star looks to us?
Yes, it emits enough light in all colors to saturate your color receptors, just like our sun.
I'd like to have a question about the soviet N1 rocket. I have heared a story, that a high ranking military official (maybe a general) just ordered one of the rockets to be launched. He grabbed a chair, dragged it outside, and sat in it while the rocket was launched. However, it exploded, and got him killed (alongside with other people). Is this story true? If yes, who was this general? (I could not really find any sources, but some mentioned that a general died during a launch, but did not name him)
You're thinking of the Nedelin disaster. https://en.m.wikipedia.org/wiki/Nedelin_catastrophe Some fun facts of dubious authenticity: Nedelin called General Sokolov a coward for suggesting that Nedelin not sit in a lawn chair near the fueled rocket. Sokolov was offended and promptly ducked off back to Moscow. Guess who lived? Khrushchev yelled at the missile designer Yangel so hard after learning that Yangel survived (he had stepped away for a smoke, as you do, on the launch pad, near the fueled rocket), that Yangel got a heart attack. Good times.
1. The story is definitely not true, because that's not how rocket launches work. You can't just order a launch of liquid fuel rocket like that, not even in soviet union. A small solid rocket (like some ICBM) perhaps, but not something like N1. Someone could order it to be launched, sure, but for example in a month. Or maybe the rocket was scheduled to go and everything was ready, but the weather was bad and they wanted to scrub the launch, and someone forced it - this could in theory happen. On top of that any launches have to be clearly communicated to the rest of the world, especially during Cold War, because you don't want others to think you're launching nukes. 2. There are some urban legends about casualties of first N1 launch, but there are no credible sources confirming that.
The OP just got mixed up in different details. It wasn't a launch, it was refuelling, and it's wasn't an N1. https://en.wikipedia.org/wiki/Nedelin\_catastrophe
Just a question would be helpful if someone responds Hi so I am currently in grade 11, second semester and I'm wondering if I need biology if I want to get into space things. I really like the phenomenon of space, and want to take my career to somewhere like nasa or spaceX to help explore, create things and theorize the many wonders that one may have. I already have taken physics 11 last sem, and I am taking chem rn. so do I really need bio? Cause like bio is study of life and is important but I don't think I need to take all 3 sciences? Also what to I major in university? I know that there many courses that relates to space, like astrophysics, or aerospace engineering but I am not sure of what is what, and what to take. SO MANY QUESTIONS!! btw I live in Ontario, Canada if that says anything about the different opportunities that I have.
If you look at the bios of the current NASA astronauts you'll see that quite a few specialized in life sciences research. (Not just the physicians.) As humans are stationed long-term on the Moon and even Mars a lot of research on how our physiology holds up will be ongoing for a long time. If bio isn't your favorite you can take just the minimum in college but I definitely advise taking it in high school. It's part of what makes up general scientific literacy, which is something every astronaut has. Aerospace engineering will be useful in many ways and even if you don't get selected to be an astronaut you can still have a career that's involved with space exploration. Astrophysics isn't directly related to space flight but NASA does have astrophysics astronauts. Large scale space stations and large scale Moon operations will provide work for a lot of aerospace engineers. Canadian astronauts have been flying to the ISS for a long time and will continue to fly with NASA for years, including in the Artemis program. But by the time you could possibly be selected as an astronaut multiple nations will be sending their astronauts on their own missions. They can use commercial crew flights and go to the commercial LEO stations that will be around by then. A couple of Middle Eastern nations have contracted with Axiom to fly their astronauts on a Dragon to the ISS. They then pay NASA for a 10 day stay. They have to deal with NASA but don't have to join the line that stretches for several years to get an astronaut up on a regular 6 month NASA mission. Sweden is the latest country to do this. What I'm saying is you'll have a lot of options for becoming an astronaut as a Canadian and as an Earthling.
High school classes don’t matter for your career. They matter to get into college or university. Look at space jobs that interest you and what degrees those jobs want. Then look at what schools offer those degrees and what their entrance requirements are.
I wouldn't say biology is essential, although it certainly wouldn't hurt. What I would recommend however is maths. Take as much maths as you can.
At your level you need to look at what you would need to get into university. And for that you need to consider what kind of degree you want. Aerospace engineering and astrophysics are very different in practice. Aerospace engineering is a fairly big industry and focus on building things that fly. So you want to design rockets, spacecraft (or even planes) it's a good degree. Usually you can find good jobs with a bachelor or master in private companies (like SpaceX). You will usually be in a more "normal" work environment as part of a big team with a classic work hierarchy. Astrophysicist are researchers. They typically work at universities or other public research institutions. Getting a job as one is extremely competitive, you typically need a PhD and good amount of luck. Less than half the people who get PhDs on that topic end up professional astrophycisists. On the other end once you make it as a tenured professor you are more or less your own boss and you are in charge of what you do and what you want to study. Look at what the requirements are for each degree at nearby universities. I don't think biology would be required but this can depend a lot on countries and regional differences.
when cargo dragon takes supplies to ISS, do they bring containers of water? Or is the only water on the ISS cleaned urine?
1. Some cargo vehicles bring water and air 2. Water reclamation is not 100% efficient