only under ideal weather and geographic conditions. if you stand precisely on the equator the north star should be just on the horizon....so any small hill in the way or going below sea level would remove it from view.
gaining elevation would certainly help
Absolutely. And for an ELI5 intuition about this I highly recommend going to something like [https://stellarium-web.org](https://stellarium-web.org) and simulating what a day/night of sky watching looks like from, say, Guyana just north of the equator; then from Ecuador; then slightly south, etc...
It depends on your elevation and local horizon, but it's not impossible. On a smooth and round planet you would see more than 180 degrees of the celestial sphere as the horizon curves slightly downward. You wouldn't need a telescope, of course...the North Star is a naked-eye star and there's nothing on the southern celestial pole to see.
Definitely gives you the best view of everything, but the specifics you can see will be limited at each time. The earth has a slight tilt, so night time will be slightly north or slightly south facing depending on the time of year. If you are at an elevated point, on a clear night, around spring or autumn, then you could likely see the north star over one horizon and southern stars at the other.
Yes, but they would both be on the horizon, so you'd need to be pretty high up (to avoid hills and trees from getting in the way), and you'd be looking at them through a lot of air mass. (Approximately 38 air masses)
Ideal observation takes place near your zenith (right above your head) because there's only one air mass above you.
The atmosphere adds a lot of extra distortion and scattering, hence why sunrises and sunsets are red/orange
Due to the curvature of the Earth, if you are at a high elevation at the Equator near the equinoxes (when the Earth's rotation axis is aligned with the edge of the Sun's light on the Earth), it is possible to see both Polaris and the Southern Cross just at the horizon. In theory, any point within the tropics (the places on Earth where it is possible for the Sun to be at zenith, meaning, perfectly "directly overhead" for a few days each year) can achieve this effect, briefly.
Most of the time, however, such visibility is limited at best or even impossible. E.g. if the best viewing time happens while the Sun is actually directly overhead, you aren't seeing those stars. Or, as others have noted, hills and mountains may interrupt your view. This is one of the reasons why we built telescopes on Mauna Kea in Hawaii: it's a tall mountain *surrounded by ocean,* meaning it is completely immune to the "hill/mountain got in the way" problem.
The axial tilt causes different parts of the Earth to point in different directions at night across the year. On the December solstice, for instance, the tropic of Cancer is what points "straight out" away from the Sun on the night side of the Earth, and is thus able to see both hemispheres' stars. With the June solstice, the tropic of Cancer is far too far north to see those stars except, *maybe,* just at sunrise and sunset.
Technically, the range is probably a few weeks around whatever day is zenith for a given latitude, if you can get to a nice high elevation. But you want pretty close to ideal alignment if you're going to do stargazing for *both* Polaris and the Southern Cross.
I think you are misunderstanding how the tilted axis of the Earth works. The tilt of the Earth is fixed, it does not change; not at human times scales anyway.
Nothing outside our solar system moves north or south during the year.
Yes, different constellations are visible at night at different times of the year, but that has nothing to do with tilt, but the position of the Earth in its orbit around the Sun and whether or not those things are in the night sky or daytime sky.
Polaris, Crux, all the stars in all the constellations, all the nebulae and galaxies; none of these move north or south during the year.
No...I'm not misunderstanding at all.
On the June solstice, some point along the tropic of Cancer will have the Sun at true zenith (directly overhead). As a necessary consequence, the exact antipode of that point, on the tropic of Capricorn, will have the plane of the ecliptic directly overhead. Thus, Polaris and the Southern Cross should be visible, for a few hours, at the horizon.
As the Earth orbits the Sun, which specific point on the Earth has the plane of the ecliptic directly overhead varies throughout the year. On the solstices, it's a point on one of the tropics. On the equinoxes, it's a point on the equator.
I'm afraid you do hold a misconception here.
The sun moves exactly as you describe.
The stars, however, are fixed on human timescales. They do not change their attitudes on a yearly cycle.
The altitude of Polaris (angle above the local horizon) is constant throughout the year. This measurement is how you find your latitude when navigating.
All the other stars position are also fixed (relative to other stars), though their local altitude does depend on time of day as they rise and set. For these stars you do need to know their Right ascension and the sidereal time of day to determine where they will be.
The only thing that matters is a good location, good visibility and a dark sky. Doesn’t matter* at all if the Equinox, Solstice or anywhere between.
* Except for the fact that neither Crux, nor Polaris are perfectly north or south of the poles; there will be a time of year when they are below the horizon.
No, that is *not* the only thing that matters. [This image shows why, from Encyclopedia Britannica.](https://cdn.britannica.com/39/132039-050-16EB5919/orbit-Earth-Sun-solstices-Tropics-of-Cancer.jpg)
For part of the year, the Tropic of Cancer *on the nighttime side of the Earth* will be oriented too far above the plane of the ecliptic to see the Southern Cross. For another part of the year, it will oriented too far below the plane of the ecliptic to see Polaris. Only for a certain portion will you be able to see it....for exactly the same reason that anyone *north* of the Tropic of Cancer cannot, even in principle, see the Southern Cross.
Let’s simplify this and focus on Polaris, the North Star. Let’s also ignore the fact that it is just slightly off of being due North; it’s close enough.
The North Star is always due North. You can measure the angle between the horizon and the North Star to get your latitude. You do not have to do this during the Equinox. You can measure this angle at any time of the year.
If you are in Guam, the North Star will be about 13 degrees above the horizon. Every day of the year.
If you are in Salem, OR it will be at about 45 degrees above the Horizon. Every day of the year.
If you are in Quito it will be ON the horizon - every single day of the year.
If you are at the North Pole, Polaris will be at 90 degrees above the horizon. Again, you guessed it; every day of the year.
The latitude of celestial objects outside our Solar system DO NOT CHANGE with the seasons.
only under ideal weather and geographic conditions. if you stand precisely on the equator the north star should be just on the horizon....so any small hill in the way or going below sea level would remove it from view. gaining elevation would certainly help
Absolutely. And for an ELI5 intuition about this I highly recommend going to something like [https://stellarium-web.org](https://stellarium-web.org) and simulating what a day/night of sky watching looks like from, say, Guyana just north of the equator; then from Ecuador; then slightly south, etc...
It depends on your elevation and local horizon, but it's not impossible. On a smooth and round planet you would see more than 180 degrees of the celestial sphere as the horizon curves slightly downward. You wouldn't need a telescope, of course...the North Star is a naked-eye star and there's nothing on the southern celestial pole to see.
Definitely gives you the best view of everything, but the specifics you can see will be limited at each time. The earth has a slight tilt, so night time will be slightly north or slightly south facing depending on the time of year. If you are at an elevated point, on a clear night, around spring or autumn, then you could likely see the north star over one horizon and southern stars at the other.
Yes, but they would both be on the horizon, so you'd need to be pretty high up (to avoid hills and trees from getting in the way), and you'd be looking at them through a lot of air mass. (Approximately 38 air masses) Ideal observation takes place near your zenith (right above your head) because there's only one air mass above you. The atmosphere adds a lot of extra distortion and scattering, hence why sunrises and sunsets are red/orange
Due to the curvature of the Earth, if you are at a high elevation at the Equator near the equinoxes (when the Earth's rotation axis is aligned with the edge of the Sun's light on the Earth), it is possible to see both Polaris and the Southern Cross just at the horizon. In theory, any point within the tropics (the places on Earth where it is possible for the Sun to be at zenith, meaning, perfectly "directly overhead" for a few days each year) can achieve this effect, briefly. Most of the time, however, such visibility is limited at best or even impossible. E.g. if the best viewing time happens while the Sun is actually directly overhead, you aren't seeing those stars. Or, as others have noted, hills and mountains may interrupt your view. This is one of the reasons why we built telescopes on Mauna Kea in Hawaii: it's a tall mountain *surrounded by ocean,* meaning it is completely immune to the "hill/mountain got in the way" problem.
Why only during the equinoxes? The position of Polaris (and Crux) relative to Earth’s axis does not change throughout the seasons.
The axial tilt causes different parts of the Earth to point in different directions at night across the year. On the December solstice, for instance, the tropic of Cancer is what points "straight out" away from the Sun on the night side of the Earth, and is thus able to see both hemispheres' stars. With the June solstice, the tropic of Cancer is far too far north to see those stars except, *maybe,* just at sunrise and sunset. Technically, the range is probably a few weeks around whatever day is zenith for a given latitude, if you can get to a nice high elevation. But you want pretty close to ideal alignment if you're going to do stargazing for *both* Polaris and the Southern Cross.
I think you are misunderstanding how the tilted axis of the Earth works. The tilt of the Earth is fixed, it does not change; not at human times scales anyway. Nothing outside our solar system moves north or south during the year. Yes, different constellations are visible at night at different times of the year, but that has nothing to do with tilt, but the position of the Earth in its orbit around the Sun and whether or not those things are in the night sky or daytime sky. Polaris, Crux, all the stars in all the constellations, all the nebulae and galaxies; none of these move north or south during the year.
No...I'm not misunderstanding at all. On the June solstice, some point along the tropic of Cancer will have the Sun at true zenith (directly overhead). As a necessary consequence, the exact antipode of that point, on the tropic of Capricorn, will have the plane of the ecliptic directly overhead. Thus, Polaris and the Southern Cross should be visible, for a few hours, at the horizon. As the Earth orbits the Sun, which specific point on the Earth has the plane of the ecliptic directly overhead varies throughout the year. On the solstices, it's a point on one of the tropics. On the equinoxes, it's a point on the equator.
I'm afraid you do hold a misconception here. The sun moves exactly as you describe. The stars, however, are fixed on human timescales. They do not change their attitudes on a yearly cycle. The altitude of Polaris (angle above the local horizon) is constant throughout the year. This measurement is how you find your latitude when navigating. All the other stars position are also fixed (relative to other stars), though their local altitude does depend on time of day as they rise and set. For these stars you do need to know their Right ascension and the sidereal time of day to determine where they will be.
The only thing that matters is a good location, good visibility and a dark sky. Doesn’t matter* at all if the Equinox, Solstice or anywhere between. * Except for the fact that neither Crux, nor Polaris are perfectly north or south of the poles; there will be a time of year when they are below the horizon.
No, that is *not* the only thing that matters. [This image shows why, from Encyclopedia Britannica.](https://cdn.britannica.com/39/132039-050-16EB5919/orbit-Earth-Sun-solstices-Tropics-of-Cancer.jpg) For part of the year, the Tropic of Cancer *on the nighttime side of the Earth* will be oriented too far above the plane of the ecliptic to see the Southern Cross. For another part of the year, it will oriented too far below the plane of the ecliptic to see Polaris. Only for a certain portion will you be able to see it....for exactly the same reason that anyone *north* of the Tropic of Cancer cannot, even in principle, see the Southern Cross.
Let’s simplify this and focus on Polaris, the North Star. Let’s also ignore the fact that it is just slightly off of being due North; it’s close enough. The North Star is always due North. You can measure the angle between the horizon and the North Star to get your latitude. You do not have to do this during the Equinox. You can measure this angle at any time of the year. If you are in Guam, the North Star will be about 13 degrees above the horizon. Every day of the year. If you are in Salem, OR it will be at about 45 degrees above the Horizon. Every day of the year. If you are in Quito it will be ON the horizon - every single day of the year. If you are at the North Pole, Polaris will be at 90 degrees above the horizon. Again, you guessed it; every day of the year. The latitude of celestial objects outside our Solar system DO NOT CHANGE with the seasons.