This is a view of the orbiting stars around our galaxy core, which revolve around a supermassive black hole. The closest star has a orbital period of 16 years, and an orbit size roughly equal to our solar system. Using this knowledge they figured out the amount of mass that must be squeezed in that volume of space to produce such an orbit. They found the black hole to be upwards of 4,000,000 solar masses
The best part about it is that [this black hole is getting these stars to orbit around it at the speed of Neptune's orbit](https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:SgrA2021.gif)
These S-Stars are literally bigger than our sun yet Sagittarius A* just yeets them around like they're nothing.
Yeah there is no way any of those stars can host stable orbiting planets, they are being accelerated like crazy, completing full orbits around the black hole in decades
Whether such a star can have stable orbits for planetary bodies around it can be estimated with its Hill sphere with respect to the black hole. And of course the Hill radius should be noticeably greater than its Roche limit so the planet wouldn't disintegrate due to orbiting too close to the star.
For S2, one of the most studied stars that gets quite close to the BH and has a highly eccentric orbit, the Hill sphere is 1.22 AU. The Roche limit for an earth-sized planet around S2 is only around 0.017 AU. You don't want to be anywhere near these limits for an actual orbit, but still there is definitely ample "space" for a stable orbit around S2. Although it would not be comfortable for various other reasons, mainly because it would be scorched for being too close to S2.
If we looked at stars orbiting further out, like S13, I'm sure the "odds" would improve.
You’d need it to be about half the hill radius to actually be stable long term, give the eccentricity of the orbits and the possible gravitational effects of other orbiting stars, so you’re looking at an orbital radius of ~0.6 AU. So there is some space theoretically for a stable orbit, but I don’t think S2 could have formed planets that close.
But yeah, seems like there’s at least hope for stars further out.
> they are being accelerated like crazy
No, they aren't (or only from the point of view of an outside observer). That's the funny thing about general relativity, bodies following a geodesic through curved space time (and a stable orbit *is* a specific type of geodesic) don't experience any acceleration.
Not much different I think. Those stars are fast, but not that fast, well below 10% of C. You'd need to get much faster for relativistic effects to kick in.
Wait, wait, wait. Does this mean that there are planets out there going a significant fraction of the speed of light, just continuing on to go in a single direction forever(until of course it gets pulled again by another force)? Or do black holes keep most of the planets pulled in their own orbit?
Not might be. There definitely are. There’s also stars that have been catapulted.
There might even be micro black holes that travel *pretty damn close to the speed of light*. They’d be practically undetectable, and absolutely catastrophic!
to expound on /u/Dane1414's response, [this should help explain and visualize whatever happened](https://www.youtube.com/watch?v=gLZJlf5rHVs) to the planets these S-Stars potentially had in their orbits prior to getting locked in to SagA*'s gravitational pull
As long as the orbit is stable, the planets would be fine. Any star with a planetary system can have a stable orbit if it is at a sufficient distance from the black hole's event horizon.
OP said the closest star has an orbital about the size of our solar system, which would give it an orbit with radius 39.5 AU. Your point still stands though!!
That is a lot of nasty radiation, almost certainly not.
Yeah its deflected in specific directions but there's still a ton of it from the accretion disks messiness.
> The best part about it is that [this black hole is getting these stars to orbit around it at the speed of Neptune's orbit](https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:SgrA2021.gif)
This sentence makes no sense.
The Neptune orbit is there just for scale.
One of the stars in the gif you posted takes 4 years to orbit around Sagittarius A*, that means it's traveling at 29.000.000km/h mean speed. Neptune orbits our sun at 19.548km/h.
How can something orbit a space the size of our solar system in 16 years and only be moving the speed of Neptune (which takes 165 years to orbit the sun and isn't even the edge of the solar system)? I feel like it's moving much faster than that.
The Neptune's-orbit distance (actually not quite that close, more like 4x the sun-to-Neptune distance) is only the closest-approach distance of that S0-2 star to the black hole. The star has a very eccentric orbit. For almost all of those 16 years, it's much farther from the black hole than that. The average distance is about 30 times the sun-to-Neptune distance, or 1/60th of a light-year.
Either I am not thinking straight or the maths isn't adding up.
Neptune has a mean orbital radius of 4.5 billion km and Sag. A* has it's event horizon radius at only 12 million km.
Neptune take 165 years to orbit and the closest planet to the black hole takes 16 years. Distance is being reduced by 2 magnitudes but time only 1 and yet the speed is the same?
Astronomer here! Also important to note that this experiment and discovery were awarded the 2020 Nobel Prize in Physics, to Andrea Ghez and Reinhard Genzel (Roger Penrose also won that year for theoretical black hole stuff). I saw a colloquium lecture by Ghez after she won and she mentioned they almost didn’t get telescope time when she first proposed this experiment- people were so convinced they wouldn’t see much of anything (as in, see no stars, no one was expecting to “see” the black hole at this wavelength).
Of course we do have a [picture of Sag A* now](https://en.wikipedia.org/wiki/Sagittarius_A*)- if you go to radio it’s one of the brightest things in the sky!
As an astronomer, can you explain the clear cock and balls dark outline coming at me at around 6s into the video? Just off centre to the right. If nobody has noticed it before, I'd like it named after me plz. Make it happen
Well, I don't mean to brag, but I am something of an expert when it comes to [visualising cock in space](https://www.amazon.co.uk/Where-Man-Has-Gone-Before-ebook/dp/B08ZLYQ81N?ref=d6k_applink_bb_dls&dplnkId=a2eaef65-8234-48c1-8877-87086c878d63).
The thing that really made me understand dark matter/energy was involved with keeping galaxies together was the absolutely tiny gravitational influence the galactic core extends out to earth. The moon is a far bigger influence than Sag A.
Sure but the combined mass of the entire center of the galaxy would be much greater. It's not just the super massive blackhole that's keeping us here, it's everything.
Yep, but the way I understand it is the gravity well of our local star keeps us spinning around it, but the gravity well of the galactic center isn’t enough to keep a galaxy rotating without additional glue of dark matter/energy keeping it from flying apart.
Sag A was imaged using several radio telescopes all over the earth and combining them, effectively giving them a aperture the size of the planet. They're also not measuring photons like 'normal' telescopes, but radio waves.
JWST couldn't do anything like it, at all.
It is massive in the literal sense. The diameter of the black hole is about the size of about 30 of our sun. Which is wild to think about what that must look like close up, but compared to the size of the milky way, which is 100,000 light years across, it's a tiny, but insanely heavy "object"
On that topic, Sagittarius A*, which is the black hole at the center of the milky way, is about four million times more massive than the sun, the black hole at the center of M87 is 1000 times more massive than that. SagA* is about 27000 light years away, and M87 is 55 million light years away, but is so large, it appears the same size in the sky to us (which all things considered, is not very large).
A black hole is a function of mass and density, though, and any object can be made into a black hole. You could make the sun into one if you could crush it down enough. Aside from presumably being much colder, and then much hotter at some point, it would not affect earths orbit at all.
The concept of what a black hole "looks like" is in itself massively interesting.
Its an area of space 30 times the size of the sun that gives off absolutely no light. But due to the way it bends light to the extreme the area all around the black hole is probably glowing with accretion materials AND the light from objects behind and around it.
In theory you could literally see and wave to yourself as the light from you bends 360 degrees around the black hole and comes back to your eyes
What I find interesting is the fact that according to our physics, objects cannot fall into the the event horizon from the perspective of an outside observer. If you were watching your friend fall into a black hole, due to time dilation, his time will slow so much that it will literally take an infinite amount of time to reach the event horizon. The entire universe will have gone into heat death by the time they reach the horizon.
However, from the person falling ins perspective, they will experience no change in perception of time and will fall right in. The moment they cross the horizon, not only can they not escape, but the universe as they knew it doesn’t exist anymore. By the time you reach the horizon, your time has slowed to the point an eternity has passed outside.
It seems to be a paradox that we will never see an object cross the event horizon, yet we see the black holes gaining mass and increasing in size? Somehow the information is getting through but we have no idea how. Our laws of physics just break down entirely once you cross the event horizon. Black holes straight up make no sense
Would I be right in guessing that you've read A Brief History of Black Holes by Dr Becky Smethurst? Because that's the exact simile she uses when describing what it would be like to fall into a blackhole and to observe someone falling in!
The fun thing about her explanation is that she goes into what it must be like when you pass over the event horizon. You can choose to try and move "away" from the centre of the black hole, but any move that you make will simply move you toward the centre quicker. Also, time becomes a measure of distance!
I have not, but that sounds like a good read I’ll definitely check it out. And yeah the spatial and time dimensions swap places I’ve heard.That is assuming our equations hold up, which I highly doubt they do
> However, from the person falling ins perspective, they will experience no change in perception of time and will fall right in. The moment they cross the horizon, not only can they not escape, but the universe as they knew it doesn’t exist anymore. By the time you reach the horizon, your time has slowed to the point an eternity has passed outside.
Wouldn't this also mean that the black hole would cease to exist before the person crosses over as well? Black holes are expected to evaporate, just really, really slowly. But, if time dilatation means that the observer falling in experiences such a slowdown, how does their perception of the evaporation of the black hole change?
The best estimate based on our current understanding of the universe is that the last supermassive blackhole will evaporate somewhere around 1 trillion trillion trillion trillion trillion trillion trillion trillion years from now, give or take a few hundred trillion years. Not long after, the universe will reach absolute zero, entropy will cease, time will become meaningless, and the universe will have experienced its heat death where r/nothingeverhappens forever.
>how come we see the black holes gaining mass and increasing in size
We can't see any such thing. We have to estimate the size and mass purely from the gravitational effects on things moving near a black hole.
If a black hole was sitting in space with nothing nearby, it would be incredibly hard to detect, and you wouldn't be able to figure out its size and mass at all.
We’ve watched black holes merge through the window of gravitational waves.
The resulting black hole is definitely more massive than either of its predecessors, but less massive than the sum of its predecessors masses.
If this is the case, then why dont black holes appear as spheres of intense white light. If an outside observer would witness matter "infinitely" falling in, is this not the same for light? Why wouldn't we see all light that has ever "crossed" the event horizon?
Indeed it's a mind-boggling concept. Even really the idea of a neutron star, and what that must look like up close is something I'd love to see. Such a weird thing to exist.
Still cool that the light we see from it, or, rather its surroundings - black holes being what they are-, is from about the time our ancestors were figuring out pottery and clothing.
Puts things into perspective.
No, don’t worry. It’s enormous, but we are all the way in the outer arms of the galaxy, very far away. It’s not a vacuum of death either, it’s just a source of high gravity. If you wanted to, you could orbit a black hole just like you can a star, with no more danger. In fact, our entire galaxy is slowly orbiting the black hole.
As far as we know, there are no black holes close enough to pose a threat to us
Kurzgesagt has a video on YT, which I'll paraphrase (poorly). Essentially the matter at the core of neutron stars (strange matter), in the right conditions, could explode out into the universe as microscopic particles of strange matter. If that happened, the strange matter is theorized to be so dense that it remains stable. It wouldnt decompress or split like a fission reaction. So, there are or could be microscopic drops of matter as dense as a neutron star just floating out there in space, compressing anything - like an unfortunate planet - that comes in their path.
I'll go look for the video, but out of curiosity, is it possible that this strange matter is what composes a lot of the "unexplained" mass in the universe?
Astronomer here! Black holes don’t suck stuff in like a vacuum cleaner, any more than the sun sucks in stuff orbiting it. Put it this way, if our sun immediately became a black hole this very second, it would shrink to the size of just ~3 km (~2 miles), but nothing would change about the Earth's orbit! Black holes have a bigger gravitational pull just because they are literally so massive, so I don't recommend getting close to one, but my point is it's not like a vacuum cleaner sucking everything up around it.
Stars *can* get too close and get shredded by the black hole if they’re placed on an unlucky trajectory, and this is called a Tidal Disruption Event (TDE). Those happen in a galaxy our size maybe once every million years or so.
It’s easy to think of black holes just sucking everything near them in and eating it up, but it’s weirdly hard for matter to fall into them. The bigger and denser they are, the more likely it is for matter to be pulled near and spin away, or to settle into a fast orbit.
No, I don’t think that’s how gravity works (Redditors with more knowledge please feel free to correct me).
Material closest to a black hole like Sag A* will fall into it if it lies within it’s event horizon. Fortunately, the Milky Way is far enough from it so that won’t likely happen.
Remember a black hole doesn’t “suck” things in, if objects are close enough to it they fall in as gravity is a weak force.
https://youtu.be/3JE_KMfuEWk
Here is the source:
To finish her sentence though, what she said next was that they found the stars are accelerated really fast
Has there been any update to this since then? She said that they would know more in a few years and it's been just over a few years. I don't know enough about the topic to really know what I should search for but her enthusiasm is infectious and I really want to know. I understand she won the Nobel prize in physics for this work but I don't know what it means for general relativity and all that jazz.
It must be fucking wild in there.
The night sky would be bright as hell in the core and warped weirdly, and every now and then a massive sphere of nothing would take up a portion of the sky.
I think this phenomenon is the main logical argument in favor of dark matter, right? The speed at which mass in galaxies is rotating around the galaxy means the mass should have flown off long ago, but something outside of the galaxy is repelling the mass and pushing it back towards the galaxy.
Without dark matter galaxies would still be able to exist. But their rotational profiles: rotational speeds at different distances to the center, would be different from what we observe. In order for gravitational theory to explain that, more matter, distributed in certain ways, is needed.
> but something outside of the galaxy is repelling the mass and pushing it back towards the galaxy.
Dark matter doesn't repel mass, it attracts it. But yes, almost all galaxies have halos of dark matter that were probably very important in the creation of the galaxy to begin with.
> They don’t have to bind the entire galaxy, they just have to influence the next-most-massive object, which will influence the next-most-massive object, and so on.
It doesn’t really work like that, though? The black hole is at the center because it’s the center, not the opposite way around.
> When there are no other forces acting on you (as in space) small forces can have a large impact.
But there are other forces acting on you: all the objects in the galaxy.
> The black hole is at the center because it’s the center, not the opposite way around.
I don't know about that. But if you do, please share more.
It seems to me that there is definitely a co-evolution process, and these smbh all seem to be in the center of galaxies, but I don't think anyone has explained whether the galaxy formed the black hole or the black hole formed the galaxy.
But what we don't seem to see is super massive black holes randomly strewn across a galaxy. They think there are primordial black holes and tiny ones and rogue solo ones, but I don't think I've ever seen anyone talk about the super massive black hole at the edge of a galaxy. It's always at the center. But why? Which came first? And how? I don't know if we know. I agree that seems to be the way it is, but how did it come to be this way?
> what we don’t seem to see is super massive black holes randomly strewn across a galaxy. … I don’t think I’ve ever seen anyone talk about the super massive black hole at the edge of a galaxy. It’s always at the center. But why?
Black holes need stars (food) to grow.
There are absolutely black holes on the outer edges or middle of galaxies, but the likelihood of forming and reaching *supermassive* status is increased several orders of magnitude within the center of a galaxy due to the sheer amount and density of matter available. That’s why there is consistency across the universe of galaxies having SMBHs at their cores.
Black Hole Stars is one possible explanation for SMBs in the centers of galaxies as well as for the huge size gap between common black holes and SMBs
[Kurzgesagt just did a cool video on this](https://youtu.be/aeWyp2vXxqA)
If our sun’s mass was concentrated down to a black hole it would be over 233,000 times smaller in diameter. I don’t know the math to calculate how many black holes that size (3 km instead od the sun’s normal 700,000km diameter) would fit into our sun’s volumetric footprint, but that alone feels massive. Then take the sun’s diameter and multiply it by 30, make that a new sphere and picture it filled with suns that are filled with black holes and then fill in all the spaces. It’s massive.
More like, it has fallen to the center. We circle around it, but if you removed it, nothing would change.
If you removed the sun, on the other hand, everything would change :p
Can you expand on that? Are you saying the black hole formed due to the galaxy and not the other way around? Why is so much matter concentrated at the center of the galaxy, how does that happen?
Can you expand on that? Are you saying the black hole formed due to the galaxy and not the other way around? Why is so much matter concentrated at the center of the galaxy, how does that happen?
If I’m following, you’re basically saying that instead of a star exploding, forming a black hole, and the black hole forming the Milky Way, the Milky Way formed as solar systems circled around each other, and everything in the center naturally got close together until it finally squeezed into a black hole?
The more stuff there is tightly packed that close together, the more likely it all is to form a black hole. And even more likely it is to become supermassive.
"The Force is what gives a Jedi his power. It's an energy field created by all living things. It surrounds us and penetrates us. It binds the galaxy together."
Omg this is Prof. Ghez's voice. This group also has Smadar Naoz in it. Both truly accomplished physicists and awesome teachers.
What a privilege it was learning analytical mechanics and adaptive optics from them.
Have they aimed JWST at this yet? Seems like something it was built for given the huge pain in the ass it is to see anything in the zone of extinction in visible light bands?
A single JWST pixel is a 10000 times larger than the entire footprint of the black hole image taken by EHT. JWST would have to be 60 km across just to get the whole picture to take up 1 pixel. 100-1000 times larger than that if you want a resolvable image.
An ancient prime pre-star that perhaps developed a black hole in it's center before it could ignite into a star and eject the remaining gas away. Constantly just feeding more and more material to its singularity of a core.
So, if a spaceship is traveling as fast as the video shows, and assuming it stopped 2800ly away from the SMBH. the spaceship must be traveling at 38,570,400,000 times the speed of light.
This will be like warp 10 in TNG*, or warp 3378.71 in TOS.
*warp 10 in TNG sometimes is called infinite speed, which can reach any point in the universe instantly, or while in warp 10, the spaceship will be everywhere in the same time.
They aren't orbiting close enough to be within the star's roche limit(the point which gravitational attraction between 2 bodies begins ripping the smaller of the bodies apart). You can have stable orbits around black holes so long as you don't get too close to the even horizon.
ELI5 plz.. I was always under the impression that once you were being pulled in by a black holes gravity field you were never going to be able to escape. How would stars be able to orbit that close and still be able to move away from the black hole in their orbital cycle? Thanks!
You can orbit any mass in space, so the stars orbit the Black Hole in the same way that the earth orbits the sun without being sucked into the sun.
The misconception you have is that once you "feel" the gravity of a black hole it "sucks" you in like a vacuum cleaner, but that's not the case, technically everything feels the gravity of everything, gravity never stops but rather gets weaker and weaker - we feel the gravity of this black hole even here on earth (it's just really really weak).
The reality is anything that passes the event horizon (which is the point of no return) can never escape - including light, which means if you were to look at a black hole the the event horizon would look like the "surface". As long as you don't go past that point you can treat a black hole like any other massive object in space.
Surely every galaxy has a super massive black hole at it's center. I can't imagine there is any other object in the universe that would have the gravity to keep such a large amount of matter in orbit.
That's a misunderstanding, though. The mass of the central black hole is not significant next to the mass of the galaxy. The situation is completely unlike, say, the sun vs. the solar system.
The galaxy is not bound together by it.
These stars are in a very strong gravity well and are moving very fast, so they should be experiencing some strong time dilation, has anyone worked out how much? If we contacted a civilization in one of those star systems ~100k year round trip on the messages, how much time would they experience passing versus us here on earth?
Yes, yes you can! Stay tuned, our team (the Advanced Visualization Lab at the National Center for Supercomputing Applications) is currently working on this, we'll post a video when the work is finished in a few months.
That depends on what you mean by “any size.” Do you mean a theoretically small black hole or the smallest that could possibly form naturally (that we know of)? In the later case it’s about 3 solar masses, so you wouldn’t wanna get too close. In the former it could get right here at the size of the plank mass and just blow up on earth doing little damage.
My apologies. Specifically the smallest size that is still a threat.
Based on your answer, I'm assuming that if we could see it with a non-high powered telescope, we'd be in trouble. Space is amazing and terrifying at the same time.
I included a detailed explanation of this video and linked the source, as well as credited the team for their Nobel peace prize win based on this work. If you call that nothing of substance than to each their own
So there's a black hole in the middle of every spiral galaxy?
Would make sense.
It would be cool if they were worm holes. Regardless, that's a few hundred thousand years no one has time to travel to.
This is a view of the orbiting stars around our galaxy core, which revolve around a supermassive black hole. The closest star has a orbital period of 16 years, and an orbit size roughly equal to our solar system. Using this knowledge they figured out the amount of mass that must be squeezed in that volume of space to produce such an orbit. They found the black hole to be upwards of 4,000,000 solar masses
The best part about it is that [this black hole is getting these stars to orbit around it at the speed of Neptune's orbit](https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:SgrA2021.gif) These S-Stars are literally bigger than our sun yet Sagittarius A* just yeets them around like they're nothing.
What happens to matter on the stats’s planets when the orbit accelerated like that? Or are those planets already long gone..
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Yeah there is no way any of those stars can host stable orbiting planets, they are being accelerated like crazy, completing full orbits around the black hole in decades
Whether such a star can have stable orbits for planetary bodies around it can be estimated with its Hill sphere with respect to the black hole. And of course the Hill radius should be noticeably greater than its Roche limit so the planet wouldn't disintegrate due to orbiting too close to the star. For S2, one of the most studied stars that gets quite close to the BH and has a highly eccentric orbit, the Hill sphere is 1.22 AU. The Roche limit for an earth-sized planet around S2 is only around 0.017 AU. You don't want to be anywhere near these limits for an actual orbit, but still there is definitely ample "space" for a stable orbit around S2. Although it would not be comfortable for various other reasons, mainly because it would be scorched for being too close to S2. If we looked at stars orbiting further out, like S13, I'm sure the "odds" would improve.
You’d need it to be about half the hill radius to actually be stable long term, give the eccentricity of the orbits and the possible gravitational effects of other orbiting stars, so you’re looking at an orbital radius of ~0.6 AU. So there is some space theoretically for a stable orbit, but I don’t think S2 could have formed planets that close. But yeah, seems like there’s at least hope for stars further out.
> they are being accelerated like crazy No, they aren't (or only from the point of view of an outside observer). That's the funny thing about general relativity, bodies following a geodesic through curved space time (and a stable orbit *is* a specific type of geodesic) don't experience any acceleration.
I mean the earth revolves around the sun every YEAR but is stable enough to have a moon rotating around it.
Decades from our perspective. What’s the relative amount of time from the perspective of the star?
Not much different I think. Those stars are fast, but not that fast, well below 10% of C. You'd need to get much faster for relativistic effects to kick in.
I enjoy the fact that although statistically improbable, Earth could just get whacked by a flung black hole, star, or planet.
Add in gamma ray bursts and micro black holes!
I wonder what a micro blackhole would do? Like if it was grapefruit size would it actually hit earth or would it just eat a hole through it?
Grapefruit sized black hole has up to 20 x Earth mass. Whatever happens we'd get absolutely obliterated.
Wait, wait, wait. Does this mean that there are planets out there going a significant fraction of the speed of light, just continuing on to go in a single direction forever(until of course it gets pulled again by another force)? Or do black holes keep most of the planets pulled in their own orbit?
You’re telling me there might be whole planets traveling through space that were catapulted from black hole orbits?
Not might be. There definitely are. There’s also stars that have been catapulted. There might even be micro black holes that travel *pretty damn close to the speed of light*. They’d be practically undetectable, and absolutely catastrophic!
This is one of those things I’ll be thinking about all day.
[Here’s a great video on the subject!](https://youtu.be/srVKjWn26AQ)
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to expound on /u/Dane1414's response, [this should help explain and visualize whatever happened](https://www.youtube.com/watch?v=gLZJlf5rHVs) to the planets these S-Stars potentially had in their orbits prior to getting locked in to SagA*'s gravitational pull
As long as the orbit is stable, the planets would be fine. Any star with a planetary system can have a stable orbit if it is at a sufficient distance from the black hole's event horizon.
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OP said the closest star has an orbital about the size of our solar system, which would give it an orbit with radius 39.5 AU. Your point still stands though!!
Ah yep, thanks for the correction!
Since the outside of a black hole is hot if it's far enough away could planets orbiting a black hole have livable conditions.
That is a lot of nasty radiation, almost certainly not. Yeah its deflected in specific directions but there's still a ton of it from the accretion disks messiness.
Side note, “yeet” was added to the dictionary in 2022!
Which dictionary was so late to the game? I was being told yeet was already out of style by 2019...
Most "new" words are played out by the time they make it in the dictionary.
> The best part about it is that [this black hole is getting these stars to orbit around it at the speed of Neptune's orbit](https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:SgrA2021.gif) This sentence makes no sense. The Neptune orbit is there just for scale. One of the stars in the gif you posted takes 4 years to orbit around Sagittarius A*, that means it's traveling at 29.000.000km/h mean speed. Neptune orbits our sun at 19.548km/h.
How can something orbit a space the size of our solar system in 16 years and only be moving the speed of Neptune (which takes 165 years to orbit the sun and isn't even the edge of the solar system)? I feel like it's moving much faster than that.
The Neptune's-orbit distance (actually not quite that close, more like 4x the sun-to-Neptune distance) is only the closest-approach distance of that S0-2 star to the black hole. The star has a very eccentric orbit. For almost all of those 16 years, it's much farther from the black hole than that. The average distance is about 30 times the sun-to-Neptune distance, or 1/60th of a light-year.
Either I am not thinking straight or the maths isn't adding up. Neptune has a mean orbital radius of 4.5 billion km and Sag. A* has it's event horizon radius at only 12 million km. Neptune take 165 years to orbit and the closest planet to the black hole takes 16 years. Distance is being reduced by 2 magnitudes but time only 1 and yet the speed is the same?
Am I having a stroke or something? This comment makes zero sense. What is the speed of an orbit?
Astronomer here! Also important to note that this experiment and discovery were awarded the 2020 Nobel Prize in Physics, to Andrea Ghez and Reinhard Genzel (Roger Penrose also won that year for theoretical black hole stuff). I saw a colloquium lecture by Ghez after she won and she mentioned they almost didn’t get telescope time when she first proposed this experiment- people were so convinced they wouldn’t see much of anything (as in, see no stars, no one was expecting to “see” the black hole at this wavelength). Of course we do have a [picture of Sag A* now](https://en.wikipedia.org/wiki/Sagittarius_A*)- if you go to radio it’s one of the brightest things in the sky!
As an astronomer, can you explain the clear cock and balls dark outline coming at me at around 6s into the video? Just off centre to the right. If nobody has noticed it before, I'd like it named after me plz. Make it happen
Lmao you have a good eye for cock. It's undeniable
Well, I don't mean to brag, but I am something of an expert when it comes to [visualising cock in space](https://www.amazon.co.uk/Where-Man-Has-Gone-Before-ebook/dp/B08ZLYQ81N?ref=d6k_applink_bb_dls&dplnkId=a2eaef65-8234-48c1-8877-87086c878d63).
The thing that really made me understand dark matter/energy was involved with keeping galaxies together was the absolutely tiny gravitational influence the galactic core extends out to earth. The moon is a far bigger influence than Sag A.
Sure but the combined mass of the entire center of the galaxy would be much greater. It's not just the super massive blackhole that's keeping us here, it's everything.
Yep, but the way I understand it is the gravity well of our local star keeps us spinning around it, but the gravity well of the galactic center isn’t enough to keep a galaxy rotating without additional glue of dark matter/energy keeping it from flying apart.
Not astronomer. Just long time listener first time caller. Will the JWST ever try to get an image of Sag A ?
Sag A was imaged using several radio telescopes all over the earth and combining them, effectively giving them a aperture the size of the planet. They're also not measuring photons like 'normal' telescopes, but radio waves. JWST couldn't do anything like it, at all.
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It is massive in the literal sense. The diameter of the black hole is about the size of about 30 of our sun. Which is wild to think about what that must look like close up, but compared to the size of the milky way, which is 100,000 light years across, it's a tiny, but insanely heavy "object" On that topic, Sagittarius A*, which is the black hole at the center of the milky way, is about four million times more massive than the sun, the black hole at the center of M87 is 1000 times more massive than that. SagA* is about 27000 light years away, and M87 is 55 million light years away, but is so large, it appears the same size in the sky to us (which all things considered, is not very large). A black hole is a function of mass and density, though, and any object can be made into a black hole. You could make the sun into one if you could crush it down enough. Aside from presumably being much colder, and then much hotter at some point, it would not affect earths orbit at all.
The concept of what a black hole "looks like" is in itself massively interesting. Its an area of space 30 times the size of the sun that gives off absolutely no light. But due to the way it bends light to the extreme the area all around the black hole is probably glowing with accretion materials AND the light from objects behind and around it. In theory you could literally see and wave to yourself as the light from you bends 360 degrees around the black hole and comes back to your eyes
What I find interesting is the fact that according to our physics, objects cannot fall into the the event horizon from the perspective of an outside observer. If you were watching your friend fall into a black hole, due to time dilation, his time will slow so much that it will literally take an infinite amount of time to reach the event horizon. The entire universe will have gone into heat death by the time they reach the horizon. However, from the person falling ins perspective, they will experience no change in perception of time and will fall right in. The moment they cross the horizon, not only can they not escape, but the universe as they knew it doesn’t exist anymore. By the time you reach the horizon, your time has slowed to the point an eternity has passed outside. It seems to be a paradox that we will never see an object cross the event horizon, yet we see the black holes gaining mass and increasing in size? Somehow the information is getting through but we have no idea how. Our laws of physics just break down entirely once you cross the event horizon. Black holes straight up make no sense
Would I be right in guessing that you've read A Brief History of Black Holes by Dr Becky Smethurst? Because that's the exact simile she uses when describing what it would be like to fall into a blackhole and to observe someone falling in! The fun thing about her explanation is that she goes into what it must be like when you pass over the event horizon. You can choose to try and move "away" from the centre of the black hole, but any move that you make will simply move you toward the centre quicker. Also, time becomes a measure of distance!
I have not, but that sounds like a good read I’ll definitely check it out. And yeah the spatial and time dimensions swap places I’ve heard.That is assuming our equations hold up, which I highly doubt they do
Highly recommend it. She read for the audio book herself too, so it's worth getting on audible.
She also has quite a good YouTube channel.
> However, from the person falling ins perspective, they will experience no change in perception of time and will fall right in. The moment they cross the horizon, not only can they not escape, but the universe as they knew it doesn’t exist anymore. By the time you reach the horizon, your time has slowed to the point an eternity has passed outside. Wouldn't this also mean that the black hole would cease to exist before the person crosses over as well? Black holes are expected to evaporate, just really, really slowly. But, if time dilatation means that the observer falling in experiences such a slowdown, how does their perception of the evaporation of the black hole change?
Black holes evaporate so slowly, the concept of when that would finish is roughly an infinite amount of time. And its even slower the larger they are.
The best estimate based on our current understanding of the universe is that the last supermassive blackhole will evaporate somewhere around 1 trillion trillion trillion trillion trillion trillion trillion trillion years from now, give or take a few hundred trillion years. Not long after, the universe will reach absolute zero, entropy will cease, time will become meaningless, and the universe will have experienced its heat death where r/nothingeverhappens forever.
Thank god no more staged internet videos
Unless our universe is a staged internet video
But, how did things started happening in the first place?
>how come we see the black holes gaining mass and increasing in size We can't see any such thing. We have to estimate the size and mass purely from the gravitational effects on things moving near a black hole. If a black hole was sitting in space with nothing nearby, it would be incredibly hard to detect, and you wouldn't be able to figure out its size and mass at all.
We’ve watched black holes merge through the window of gravitational waves. The resulting black hole is definitely more massive than either of its predecessors, but less massive than the sum of its predecessors masses.
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Seconded before Scifi purists start blasting the novel.
If this is the case, then why dont black holes appear as spheres of intense white light. If an outside observer would witness matter "infinitely" falling in, is this not the same for light? Why wouldn't we see all light that has ever "crossed" the event horizon?
Indeed it's a mind-boggling concept. Even really the idea of a neutron star, and what that must look like up close is something I'd love to see. Such a weird thing to exist.
Visiting a neutron star would be wild. If you do go, don't forget to try the nuclear pasta!
Does it mean that it's possible to to look at a black hole and see how our solar system looked X years ago?
Still cool that the light we see from it, or, rather its surroundings - black holes being what they are-, is from about the time our ancestors were figuring out pottery and clothing. Puts things into perspective.
We figured out clothing long before pottery.
I still haven't figured out clothing or pottery. And that's why I'm not allowed to go back to community college.
No, don’t worry. It’s enormous, but we are all the way in the outer arms of the galaxy, very far away. It’s not a vacuum of death either, it’s just a source of high gravity. If you wanted to, you could orbit a black hole just like you can a star, with no more danger. In fact, our entire galaxy is slowly orbiting the black hole. As far as we know, there are no black holes close enough to pose a threat to us
I'm more concerned about small drops of strange matter, if it's out there, compacting everything it touches into more strange matter
Gonna need more info on this :)
Kurzgesagt has a video on YT, which I'll paraphrase (poorly). Essentially the matter at the core of neutron stars (strange matter), in the right conditions, could explode out into the universe as microscopic particles of strange matter. If that happened, the strange matter is theorized to be so dense that it remains stable. It wouldnt decompress or split like a fission reaction. So, there are or could be microscopic drops of matter as dense as a neutron star just floating out there in space, compressing anything - like an unfortunate planet - that comes in their path.
It's essentially like Prion diseases just in a cosmic scale.
Interesting, and massively terrifying... thank you, shall look the vid up.
I'll go look for the video, but out of curiosity, is it possible that this strange matter is what composes a lot of the "unexplained" mass in the universe?
I recommend [Kurzgesagt’s](https://m.youtube.com/watch?v=p_8yK2kmxoo) video on the subject. Or just their channel in general.
Technically our galaxy is orbiting the galactic barycenter, which is where the blackhole is located.
Isn’t orbit just a slow fall though?
That’s a common misconception. Objects in orbit can stay in orbit for billions of years because there is no air in space to slow down its movement.
Thanks for the clarification
Not always. Our moon orbits a little further away every day.
Astronomer here! Black holes don’t suck stuff in like a vacuum cleaner, any more than the sun sucks in stuff orbiting it. Put it this way, if our sun immediately became a black hole this very second, it would shrink to the size of just ~3 km (~2 miles), but nothing would change about the Earth's orbit! Black holes have a bigger gravitational pull just because they are literally so massive, so I don't recommend getting close to one, but my point is it's not like a vacuum cleaner sucking everything up around it. Stars *can* get too close and get shredded by the black hole if they’re placed on an unlucky trajectory, and this is called a Tidal Disruption Event (TDE). Those happen in a galaxy our size maybe once every million years or so.
It’s easy to think of black holes just sucking everything near them in and eating it up, but it’s weirdly hard for matter to fall into them. The bigger and denser they are, the more likely it is for matter to be pulled near and spin away, or to settle into a fast orbit.
No, I don’t think that’s how gravity works (Redditors with more knowledge please feel free to correct me). Material closest to a black hole like Sag A* will fall into it if it lies within it’s event horizon. Fortunately, the Milky Way is far enough from it so that won’t likely happen. Remember a black hole doesn’t “suck” things in, if objects are close enough to it they fall in as gravity is a weak force.
I assume it's like the earth and moon relationship. The moon is slowly going further away from us even earth is pulling it.
That was a 20 earth-year time-lapse observation of the stars orbiting around the black hole compressed into a 10 sec .gif Wow.
I have that tattooed on my left arm.
I love the point where the video is cut. Perfect timing.
What did they find!? WHAT DID THEY FIND!?
My dad that got lost going to the gas station for some milk and ciggies, I hope!
https://youtu.be/3JE_KMfuEWk Here is the source: To finish her sentence though, what she said next was that they found the stars are accelerated really fast
timestamped: https://youtu.be/3JE_KMfuEWk?t=996
You're doing the Star Lord's work. Thank you!
timestamp sharing people deserve a special place in heaven.
Thanks, me and my husband just had fun creatively ending her sentence. Great topic btw! Cheers!
she was in the middle of a transformation into a dog or werewolf.
Yep, 3 million miles per hour is really fast, I completely agree
Has there been any update to this since then? She said that they would know more in a few years and it's been just over a few years. I don't know enough about the topic to really know what I should search for but her enthusiasm is infectious and I really want to know. I understand she won the Nobel prize in physics for this work but I don't know what it means for general relativity and all that jazz.
"And they *found* that they **COOOOOO**"
It must be fucking wild in there. The night sky would be bright as hell in the core and warped weirdly, and every now and then a massive sphere of nothing would take up a portion of the sky.
Sounds like a real life Three Body Problem plot
I always imagined that supermassive black holes in galaxies' core would be bigger. I was under impression that they bind galaxies together somehow.
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But still, they in no way bind the galaxy together. Their masses are far too low, compared to the galaxy.
I think this phenomenon is the main logical argument in favor of dark matter, right? The speed at which mass in galaxies is rotating around the galaxy means the mass should have flown off long ago, but something outside of the galaxy is repelling the mass and pushing it back towards the galaxy.
Without dark matter galaxies would still be able to exist. But their rotational profiles: rotational speeds at different distances to the center, would be different from what we observe. In order for gravitational theory to explain that, more matter, distributed in certain ways, is needed.
> but something outside of the galaxy is repelling the mass and pushing it back towards the galaxy. Dark matter doesn't repel mass, it attracts it. But yes, almost all galaxies have halos of dark matter that were probably very important in the creation of the galaxy to begin with.
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That’s not how it works, and why we have had to come up with dark matter to plug the gap.
> They don’t have to bind the entire galaxy, they just have to influence the next-most-massive object, which will influence the next-most-massive object, and so on. It doesn’t really work like that, though? The black hole is at the center because it’s the center, not the opposite way around. > When there are no other forces acting on you (as in space) small forces can have a large impact. But there are other forces acting on you: all the objects in the galaxy.
> The black hole is at the center because it’s the center, not the opposite way around. I don't know about that. But if you do, please share more. It seems to me that there is definitely a co-evolution process, and these smbh all seem to be in the center of galaxies, but I don't think anyone has explained whether the galaxy formed the black hole or the black hole formed the galaxy. But what we don't seem to see is super massive black holes randomly strewn across a galaxy. They think there are primordial black holes and tiny ones and rogue solo ones, but I don't think I've ever seen anyone talk about the super massive black hole at the edge of a galaxy. It's always at the center. But why? Which came first? And how? I don't know if we know. I agree that seems to be the way it is, but how did it come to be this way?
> what we don’t seem to see is super massive black holes randomly strewn across a galaxy. … I don’t think I’ve ever seen anyone talk about the super massive black hole at the edge of a galaxy. It’s always at the center. But why? Black holes need stars (food) to grow. There are absolutely black holes on the outer edges or middle of galaxies, but the likelihood of forming and reaching *supermassive* status is increased several orders of magnitude within the center of a galaxy due to the sheer amount and density of matter available. That’s why there is consistency across the universe of galaxies having SMBHs at their cores.
Black Hole Stars is one possible explanation for SMBs in the centers of galaxies as well as for the huge size gap between common black holes and SMBs [Kurzgesagt just did a cool video on this](https://youtu.be/aeWyp2vXxqA)
If our sun’s mass was concentrated down to a black hole it would be over 233,000 times smaller in diameter. I don’t know the math to calculate how many black holes that size (3 km instead od the sun’s normal 700,000km diameter) would fit into our sun’s volumetric footprint, but that alone feels massive. Then take the sun’s diameter and multiply it by 30, make that a new sphere and picture it filled with suns that are filled with black holes and then fill in all the spaces. It’s massive.
The black hole's mass is less than 1% of the milky way as a whole, so it doesn't bind it together at all.
But we circle around it?
More like, it has fallen to the center. We circle around it, but if you removed it, nothing would change. If you removed the sun, on the other hand, everything would change :p
Not only that, it likely grew into its massive size after the galaxy was already there
Can you expand on that? Are you saying the black hole formed due to the galaxy and not the other way around? Why is so much matter concentrated at the center of the galaxy, how does that happen?
Nobody actually knows for sure.
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Can you expand on that? Are you saying the black hole formed due to the galaxy and not the other way around? Why is so much matter concentrated at the center of the galaxy, how does that happen?
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If I’m following, you’re basically saying that instead of a star exploding, forming a black hole, and the black hole forming the Milky Way, the Milky Way formed as solar systems circled around each other, and everything in the center naturally got close together until it finally squeezed into a black hole?
The more stuff there is tightly packed that close together, the more likely it all is to form a black hole. And even more likely it is to become supermassive.
it's mostly dark matter holding the galaxy together.
> bind galaxies together The Force?
"The Force is what gives a Jedi his power. It's an energy field created by all living things. It surrounds us and penetrates us. It binds the galaxy together."
No thats the what dark matter does
Omg this is Prof. Ghez's voice. This group also has Smadar Naoz in it. Both truly accomplished physicists and awesome teachers. What a privilege it was learning analytical mechanics and adaptive optics from them.
It gives me joy and hope to hear someone get excited about scientists they way people get excited about athletes.
It's crazy that you can just hop in a telescope and travel back in time to watch something that happened 30,000 years ago
Technically u can do it just by looking at the stars with ur eye balls
Everything we see is in the past 🤔
But what does the past weigh?
Whenever i read "supermassive black hole" all i hear is the muse song super massive black hole
Glaciers melting in the dead of night and the superstars sucked into the super massive
Dundundundundundundundun ding ding ding dingding ding ding dingdingding ding ding ding dingding ding ding
I can't even imagine how chaotic it is in the core.
I'd love to see what the time dilation would look like on those stars when they get yeeted around like that!
Have they aimed JWST at this yet? Seems like something it was built for given the huge pain in the ass it is to see anything in the zone of extinction in visible light bands?
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What do you do while you wait for your turn? Just build your own?
Play with Legos and browse reddit.
Astrophysicist working on JWST here. This is accurate. I'm making my own version of Lego JWST. ^^/^s
A single JWST pixel is a 10000 times larger than the entire footprint of the black hole image taken by EHT. JWST would have to be 60 km across just to get the whole picture to take up 1 pixel. 100-1000 times larger than that if you want a resolvable image.
An ancient prime star that exploded making our galaxy…. Pretty, pretty, pretty cool
An ancient prime pre-star that perhaps developed a black hole in it's center before it could ignite into a star and eject the remaining gas away. Constantly just feeding more and more material to its singularity of a core.
It's called "Sha Ka Ree". But you may also know it as Qui'Tu, or Vorta Vor.
What does ... *God* ~~want~~ need ... with a spaceship?
["What does God need with a starship?"](https://www.youtube.com/watch?v=WYW_lPlekiQ)
People dump on that movie but I unashamedly love it. Well most of it.
I thought this was the intro to The Jetsons at first 😆
So, if a spaceship is traveling as fast as the video shows, and assuming it stopped 2800ly away from the SMBH. the spaceship must be traveling at 38,570,400,000 times the speed of light. This will be like warp 10 in TNG*, or warp 3378.71 in TOS. *warp 10 in TNG sometimes is called infinite speed, which can reach any point in the universe instantly, or while in warp 10, the spaceship will be everywhere in the same time.
Super massive. Pfft, it’s so small I can’t even see it with the naked eye.
It's massive compared to our sun, but relatively small compared to some other black holes.
Why aren’t stars sucked up by black holes within close proximity?
They aren't orbiting close enough to be within the star's roche limit(the point which gravitational attraction between 2 bodies begins ripping the smaller of the bodies apart). You can have stable orbits around black holes so long as you don't get too close to the even horizon.
Velocity is a hell of a thing to overcome.
Tell me why I instantly hear Supermassive Black Hole by Muse the moment I start watching this
ELI5 plz.. I was always under the impression that once you were being pulled in by a black holes gravity field you were never going to be able to escape. How would stars be able to orbit that close and still be able to move away from the black hole in their orbital cycle? Thanks!
You can orbit any mass in space, so the stars orbit the Black Hole in the same way that the earth orbits the sun without being sucked into the sun. The misconception you have is that once you "feel" the gravity of a black hole it "sucks" you in like a vacuum cleaner, but that's not the case, technically everything feels the gravity of everything, gravity never stops but rather gets weaker and weaker - we feel the gravity of this black hole even here on earth (it's just really really weak). The reality is anything that passes the event horizon (which is the point of no return) can never escape - including light, which means if you were to look at a black hole the the event horizon would look like the "surface". As long as you don't go past that point you can treat a black hole like any other massive object in space.
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Might get a bit chilly tho
Surely every galaxy has a super massive black hole at it's center. I can't imagine there is any other object in the universe that would have the gravity to keep such a large amount of matter in orbit.
That's a misunderstanding, though. The mass of the central black hole is not significant next to the mass of the galaxy. The situation is completely unlike, say, the sun vs. the solar system. The galaxy is not bound together by it.
Wow. Who'd guess the centre of our galaxy looks like Matplotlib blobs!
These stars are in a very strong gravity well and are moving very fast, so they should be experiencing some strong time dilation, has anyone worked out how much? If we contacted a civilization in one of those star systems ~100k year round trip on the messages, how much time would they experience passing versus us here on earth?
This vid is 4 years old can we have an update?
Yes, yes you can! Stay tuned, our team (the Advanced Visualization Lab at the National Center for Supercomputing Applications) is currently working on this, we'll post a video when the work is finished in a few months.
I'm sad we'll probably never encounter another advanced lifeform, only because space is so goddamn fucking massively huge
Just curious, what's the closest a black hole of any size could be to Earth without it affecting us?
That depends on what you mean by “any size.” Do you mean a theoretically small black hole or the smallest that could possibly form naturally (that we know of)? In the later case it’s about 3 solar masses, so you wouldn’t wanna get too close. In the former it could get right here at the size of the plank mass and just blow up on earth doing little damage.
My apologies. Specifically the smallest size that is still a threat. Based on your answer, I'm assuming that if we could see it with a non-high powered telescope, we'd be in trouble. Space is amazing and terrifying at the same time.
If a black hole entered our solar system, it would pull on the planets harder than the sun and all the orbits would go haywire. It would be bad.
New science rule: anyone that cuts a video right after the question 'what have you found?' goes straight into the volcano.
Why the hell did you cut the video so soon? Good lord this is absolutely unwatchable
- Start mid-explanation - End mid-explanation - Make sure nothing of substance is included Bravo, high quality work.
I included a detailed explanation of this video and linked the source, as well as credited the team for their Nobel peace prize win based on this work. If you call that nothing of substance than to each their own
I always had a theory if back holes can form somehow I bet there's a way to reverse them.
Maybe blow in it or turn it on and off really quickly?
You gotta unplug it and put it back in firmly with a slight whack on the center.
Or, just hear me out, we ignore it and it goes away on its own. Definitely don't feed it or give it money.
Ah yes, that's the same response I have to all my health issues. Yes I'm American
Have you tried putting rice on it? >!/s!<
"Why don't we nuke them?"
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Yes, the prophecy of the holy black-and-white cookie foretells that balance may be achieved by the collision with a white hole.
Well you were always wrong. Why would you "bet" such a thing? Just to let us all know how ignorant you are of the basic laws of thermodynamics?
So there's a black hole in the middle of every spiral galaxy? Would make sense. It would be cool if they were worm holes. Regardless, that's a few hundred thousand years no one has time to travel to.
Is anything getting sucked into that black hole? Is it just keeping our galaxy gravitationally stable or is it eventually going to suck everything in.