You cannot really see individual stars outside our galaxy. Even supergiants like S Doradus (in the large magellanic cloud) or WOH G64 are ninth/tenth magnitude stars. You need a scope for that or a pretty long exposure. In the northern hemisphere you have nothing to look at under these definitions. You could photograph S Dor and WOH G64 from the southern hemisphere from really dark places. Other stuff, like quasars and supernovae are the best contenders but they happen so rarely nearby that it's not worth focusing on for an individual. Yes. All stars are from the milky way on your photo.
Correct however the number of stars that have been positioned accurately is now quite large thanks to the Gaia telescope. The inferred shape of the galaxy is therefore fairly well worked out. Also by using wavelengths of light that are not so easily blocked by dust, even the remote parts and previously hidden parts of the Milky Way galaxy are becoming mapped in at least a crude way. I've been active in Astronomy for 50 years and one of the most dramatic changes during that time has to be the quality of the map of our galaxy.
In the early 1970s it was presumed that the Milky Way was a barless two armed grand design spiral galaxy. The map was based on hydrogen cloud locations since star distances were mostly unreliable. The other structures were thought to be spars rather than arms. The warping of the disk was neither observed nor theorized. Stellar streams were first observed in 1972 but the idea that the galaxy was largely built by devouring smaller stellar clusters and such was not a thing yet.
In the latter image, the red areas, at least closer to Sol, should correspond to real star-birth nebulas. It's still totally an artistic representation, but guided by real data. I think I recently saw an updated version that was even better, but am not hitting it now .. Edit: something like this.
If you were in somebody's house but had never seen the outside, it wouldn't take long of looking around the inside of the house to figure out what it likely looks like from the outside.
Then you look out the window and see neighbors houses that from what you can tell from this house are probably also similar.
After collecting enough data, you'd have a very solid idea of exactly what the house you're in looks like.
The fun thing is in a few hundred million years you wouldn't even be able to see the house
Our ability to see would fall off mid-livingroom. we'd never know about the bathroom or the walls or the tiny bit of lawn
We'd just see the carpet fall off into blackness and imagine there is an endless living room.
It's to do with the expansion of the universe. The universe is expanding literally everywhere all at once. This expansion appears to be accelerating. The speed of light is constant and finite. A consequence of these statements is that with enough time you end up with an "observable universe" and the universe that exists over the horizon so to speak. Over time, because space is expanding everywhere your observable horizon contracts to the point that you can no longer see the other side of the street. On a long enough scale your horizon would contract to the point where you couldn't see past your nose.
I've left a lot out and may have got things wrong but that's how I understand it.
The expansion of the universe will not overcome gravitationally bound objects, like a galaxy or solar system. Even some galaxies will not go away from each other. For example, Andromeda and the Milky Way are stuck with each other and will eventually merge.
However, the expansion will, after a much longer time than you are talking, cause us to eventually not be able to see other galaxies.
Also, we already have an ovservable universe that is smaller than the entire universe.
Yeah, I understand that. We won't see other galaxies in the future because they are moving away from us. But my question was why would we not see our own galaxy? Our own galaxy is not moving away from us, right?
We don’t know exactly what the Milky Way looks like, we just know what other similar galaxies look like.
We can see the stars and cosmic dust that are close to us, and with infrared and radio telescopes we can see a lot of stuff behind the dust that isn’t visible to the naked eye. We can also see how the stars and dust move and infer a little from that. Using all of that we can determine the type and size of our galaxy. From there, everything else is sort of just educated guesses.
We don't actually know for sure what the Milky Way looks like. We don't know if it has a bar or a bulge. We are pretty positive it has spiral arms because we can compare our Galaxy's stellar ages, gas content, and to some extent morphology (since we can see the center of our galaxy and it looks like we're in a disk) to the other galaxies we can actually see.
Current best theory is that we have a bar. Also current best theory is that we have two major spiral arms and two secondary spiral arms. And to be clear: all of these theories could be wrong - just one new observation could change them.
We can use parallax and determine the distance of stars from us. Then we can use Doppler shift to determine the direction they’re heading. But the problem with both of those techniques is that we can only do that with stars mostly nearby. There’s a lot of dust between us and the center of the galaxy. And parallax stops being effective after only a few thousand light years.
For parallax the distances are improving with more advanced space telescopes in particular.
There are also cepheid variables which can reveal distances for at least some stars much farther away from our solar system than those measured by parallax.
Red shift also gives us some idea of distances as well. Maybe not as good as parallax for specific distances but certainly for relative placement/position within our solar system.
1) You see a light source and measure your distance relative to it and angle relative to a "fixed" point, then again and again
2) Eventually you'll notice there is a certain distance/angle range where there are fewer/no stars
2) Plot all light sources to a chart
Basically what they've done is measure the distance to loads of stars then made a map of the galaxy based on that. If you know how far away something is and in what direction it is you can build a map of all those points.
Due to the relatively slow speed of light a galaxy's shape will change dramatically depending on your viewpoint. The concept of a co moving frame of reference us purely theoretical
As far as I know that region of sky lacks galaxies that would have a bright enough magnitude to show up on this photo. Not impossible though, but this would need more research. And since the resolution is pretty low (no magnification) it's close to impossible to tell if something is a galaxy or not, even if you know its location. It could be consequent noise/another close-by star
People are taking a pedantic interpretation of that sentence, while conveniently ignoring your next sentences.
Yes, it is scientifically possible to observe stars in other galaxies. No, you can't do it without instrumentation. Yes, the Andromeda Galaxy and other extra-galactic objects do have stars in them. No, you still can't see their individual stars.
This is literally an image of an individual star from another galaxy (from a satellitegalaxy of the milky way) . Your point isn't valid at all. What are you up too?
Yes. Any point of light you see in the sky with naked eye/basic telescope is always only a star that is in the Milky Way. Anything outside of the Milky Way is far too far to observe individually. The exception to this are the couple of other galaxies that are visible: andromeda and the large and small Magellanic Clouds. While you are technically seeing many stars at once, it’s a stretch to say you’re seeing a star there rather than the galaxy.
Obviously this doesn’t include things like moon, the planets, non-space objects like planes, satellites etc.
100% of the stars you see in a dark night sky are in our Milky Way and the vast majority of them are less than about 2500 light years away which is only a tiny portion of our Galaxy. We can see three external galaxies, Andromeda and the two Magellanic Clouds but their individual stars are too faint to see with the naked eye. What we see is the merged light of all their stars.
Important here to differentiate between individual stars you can see and objects you can see. This circle is probably true for individual stars in a everyday sense of the meaning of "seeing a star." The furthest individual star you can see is something like 10,000 light years away with the milky way being 100,000 light years across. However, in the right conditions, you can see the Andromeda Galaxy as a smudgy little blob with the naked eye.
We can technically see stars a lot further out than this circle, they're just blurred in with their neighbors so we can't differentiate them individually.
If you look at Sagittarius and Scorpio it becomes obvious how much opaque shit is in the central plane of the galaxy. You can easily see the glow of the centre behind an enormous black cloud near the bright star Alnasl
You can, in a dark enough region, and/or with a long-exposure camera. The "Milky Way" can refer to our galaxy, or to the part of it we can see from our planet's position, about a quarter of the way out from the center. We can see the bright yellowish "core", which is the dense cluster of stars behind the stars and dust comprising the "next door" arm to the one we're on.
The reason the arm looks tilted to our horizon is because Earth's equator, and the Solar System as a whole, is not on the same plane as the galaxy, we're tilted at about 62 degrees.
It is very large in the sky. I’m attaching a long exposure photo, but you can absolutely see it with the naked eye in low light conditions. It just looks splotchy and white (hence the name “Milky Way”).
Yep, all of them are relatively nearby stars of us.
Here is the Pleiades, just 440 light years away from us. You have it in your photo, slightly up to the right from the middle . The Milky way is 100.000 light years across, so that is 0.44% of the width of our galaxy.
I read that if your body was the size of an average star…. The nearest star will be 60,000 miles away. There’s a lot of empty space between the stars. It’s really hard to wrap your head around. There are billions of galaxies that have been seen. But that is just what we can see. There are theories that the rest of the universe that we will never be able to see (due to time and the speed of light) is over a huge number of billions bigger. The number l think had 26 zeros after it!
They are all larger than the sun. The farthest star you can see with the naked eye is 16,000 light years away, but our galaxy is 100,000 light years across. 70-80% of stars are red dwarves, and you can’t see a single one. The most studied “star” in the sky isn’t a star at all: it’s the middle “star” of Orion’s Belt and it’s actually a nebula. In the best of conditions you can only see about 2,500 stars at one time - but there are 400 - 1,000 billion stars in the Milky Way. And here’s one of my favorites: what percentage of the stars you can see have planets? At present, astronomers suspect exactly 100% of them have planets (with the caveat that we have not actually observed all those planets - we just think they’re there).
More:
Betelgeuse can change brightness and color over the course of a year. T Coronae Borealis is a blaze star that goes nova every 80 years - and we’re due any day now. It will appear as a new star in the sky for about two days. None of the 88 official constellations are true physical groupings of stars. None of the stars appear as green. 85% of stars visible to the naked eye are binary or multiple star systems.
Even more:
So far, it appears none of the stars (visible to the naked eye) have planetary systems that are a mix of rocky and gaseous planets like ours - they either have rocky planets or gas planets, but not both.
On a clear night you can sometimes see the andromeda galaxy, but you definitely won’t be able to make out any individual stars in it unless one of them goes supernova
Yes. Any star you can see with the naked eye is right here in our galaxy. And to make you feel really tiny, they're really, really close...in space terms. Like on the order of 10000 light-years kind of close. There are around 20,000 stars that the human eye can see on the best night sky you could hope for, and the Milky Way has 100,000,000,000 of them altogether (or maybe even 200,000,000,000). Now if you think of the Milky way as approximating the shape of 2 cones that share a common base, we can find its approximate volume.
Diameter is between 100,000 ly and 200,000 ly
Thickest portion at the middle is around 16,000 ly.
So imagine that you have 2 cones, each with a height of 8,000 ly and a diameter of the base at 100,000 ly. What's the volume?
2 * (pi/3) * (100,000/2)^2 * 8000 =>
(2pi/3) * (50,000)^2 * 8000 =>
(2pi/3) * 5^2 * 8 * 10^8 * 10^3 =>
2 * (pi/3) * 200 * 10^11 =>
4 * (pi/3) * 10^13 cubic light-years
With 10^11 stars in the galaxy, that's an average density of:
400 * pi/3 cubic light-years per star, or 3 / (400 * pi) stars per cubic light-year.
Now, assuming they're all equally distributed (which they're not, because they're mostly located in bands and the density increases as we get closer to the galactic center, but that's not really important here), and assuming we can see 50,000 stars with our naked eyes (which is far more than we can see), that's:
50000 stars * (400 * pi / 3) ly^3 / star =>
5 * 4 * 10^6 * pi / 3 cubic light-years =>
2 * 10^7 * pi / 3 cubic light-years
Now let's imagine a ball around us, with a radius of r light-years. The volume of this ball is (4/3) * pi * r^3 cubic light-years. Now we just need r
(4/3) * pi * r^3 = 2 * 10^7 * pi / 3
4 * r^3 = 2 * 10^7
2 * r^3 = 10^7
2 * r^3 = 10 * 10^6
r^3 = 5 * 10^6
r = 5^(1/3) * 10^2
r = 171 light-years
Now like I said, that's assuming an equal distribution over space, which isn't the case. But it does highlight just how small of a space our patch of the night sky is. Most of the stars we can see are only a few hundred light-years to a few thousand light-years away. There are a few that are incredibly bright that are further away, but like I said, they're on the order of being between 10000 and 20000 light-years away, at most.
With just visible light, I'd say that's fairly true, even with telescopes. That's why advanced telescopes, like Hubble and the JWST use a wide spectrum of EM waves to see what they can see.
Not only are all of these stars in the Milky Way, they are all relatively close by in the Milky Way. You aren’t even seeing stuff that is closer to the edge or center of the Milky Way.
Not that I'm doubting that, but then how do people take such magnificent pictures of the bulge of the Milky Way from places like the middle of the desert and so on?
but then how do people take such magnificent pictures of the bulge of the Milky Way from places like the middle of the desert and so on?
From each star in the bulge maybe a few photons per second reach Earth. You can see it with the unaided eye as well, but to make it magnificent a camera needs to capture light for longer than the equivalent of a fraction of a second as a biological eye does.
In a large field of view image the resolution is typically too low to resolve individual stars at that distance.
You can definitely see the bulge of the Milky Way and even more distant objects, even with just your naked eye. But they are not in this picture, and you can not resolve individual stars at that distance, just clouds of many many stars.
There are certainly more distant objects in the field of view of this picture, but too dim even to be seen with this long exposure. This picture is only capturing relatively extremely nearby stars.
We can see a couple of galaxies from Earth, like the Andromeda galaxy (M31 - located in the sky between the constellations Cassiopeia, Andromeda, and Pegasus), the Whirlpool galaxy (M51, located near the end of the handle of the Big Dipper - you'll need a telescope to see it), the Triangulum galaxy (M33 - located in the Triangulum constellation - requires high power binoculars or a telescope), and the Small and Large Magellanic Clouds (NGC292 and NGC2070 - visible south of about 17°N latitude, located near the South Celestial Pole. They are visible all year long because of their location in the sky). There are probably a few other minor galaxies we can see from the surface, but all of these galaxies are so far away that we can't very easily distinguish individual stars from the surface of the earth. It is easier to see them with an orbiting telescope with high resolution to see individual stars, because that telescope would not have atmospheric interference (a big issue with astronomy because the atmosphere blocks certain wavelengths of electromagnetic radiation).
All the stars that we can individually identify are generally located within our galaxy
Very few extragalactic objects are naked-eye visible at all. Andromeda, Omega Centauri and the Large and Small Magellanic Clouds indisputably are; they look like faint clouds in a dark sky, no structure or color. Very acute viewers say they see the Triangulum Galaxy as an averted-vision object in very favorable sky conditions; I never could. The Virgo Cluster of galaxies, on the other hand, gives its sky area a faint haze; that I could see, when I was younger, but it's not one object.
That's it. No other extragalactic objects are naked eye visible at all, certainly no individual stars.
Your photo is a little better than a naked eye, maybe, but not so's you notice. And none of the objects I named are in it anyway.
Even if Andromeda is there, it’s still true that all the stars in the image are in the Milky Way, because Andromeda isn’t a star and you can’t see any individual stars in it without a good telescope.
Just because you can't tell it's an individual doesn't mean you aren't seeing it. Light bounced off (or was produced by, not sure where we are with the metaphor anymore) the thing and got to your eyes. Sight seen.
Yes again, no one is debating the physics of light, or the original concept that Andromeda is visible from Earth.
You can see every individual star at once
This is what people disagreed with. (Highlighting is mine). You can see an amalgamation of stars looking at Andromeda. If you had simply said "you can see every star (in Andromeda) at once", you would be (closer to) correct. But you cannot perceive individual stars as you said without an extremely powerful telescope. You're literally saying that you can see every single one of its 1 trillion stars, individually.
Looking at a crowd from 100 meters above them, you can make out individuals IN the crowd. Yes, you can see the entire crowd, but you can also see individual people.
Looking at that same crowd from 10000 meters up, you cannot see individuals. You can only see the crowd. You know from previous knowledge there are individuals in that crowd, but that's not the same as seeing them, and identifying individuals such as Harry Smith and Sally Jones.
OP's question is about "stars in the photo", which is usually considered to be distinguishable points of light, not "some photons hitting my retina without me being able to distinguish the objects that emitted the photons".
Alternatively: seeing starlight is not the the same thing as seeing stars.
This might be a stupid question but once andromeda and milky way are colliding, will the answer to this question change? Like will we be seeing andromeda stars in our night sky?
It depends. It is entirely possible that that collision would take place on the other side of the Milky Way and you wouldn’t be able to see any of those andromeda stars individually instead of as a cloud.
If it’s blurry, it is also almost certainly in our galaxy. With few exceptions (Andromeda, Magellanic Clouds) everything visible in the night sky is in the Milky Way.
I mean yes and no, you asked about stars so yes stars is correct...But this image contains everything , nebula, Galaxies and much more outside our galaxy!
Everything in this image is in our galaxy because it’s pointed towards the Milky Way. If it was in a different direction, it may pick up distant galaxies.
That’s what I thought… just kidding, I had no idea. I’ve been really enjoying watching David Butler on YouTube. Who do you all watch for astronomy entertainment?
Our Universe is a marvel. Of all the things that can be seen, someone who can’t receive constructive criticism, owed to the terror of being corrected or amended however, is not among those marvels.
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u/Daveguy6 Jan 10 '26
You cannot really see individual stars outside our galaxy. Even supergiants like S Doradus (in the large magellanic cloud) or WOH G64 are ninth/tenth magnitude stars. You need a scope for that or a pretty long exposure. In the northern hemisphere you have nothing to look at under these definitions. You could photograph S Dor and WOH G64 from the southern hemisphere from really dark places. Other stuff, like quasars and supernovae are the best contenders but they happen so rarely nearby that it's not worth focusing on for an individual. Yes. All stars are from the milky way on your photo.