How many stars in the night sky are in our galaxy?

Question

Just interested, after ready this news story http://news.bbc.co.uk/1/hi/sci/tech/6240611.stm and the fact that we can't tell what our milky way galaxy looks like because we are in it.

OK I recognise that it is difficult to put an exact number on this so lets rephrase the question slightly. What percentage, roughly, are in our galaxy at the moment?

I also assumed that galaxies would appear to be single stars in the night sky. Correct me if I am wrong?

Thank you for all the answers. You learn something new... I had always just assumed that some of the 'stars' in the sky were galaxies as well as single stars. But it turns that the only other galaxy we can just about see with the naked eye is Andromada and the Magellanic clouds.

Answer 1

Pretty much all of them, If you look in the constellation of Andromeda you might see a hazy patch, that's the Andromeda Galaxy which is the most prominent of all other galaxies outside the Milky Way.
Everything else is within the Milky Way.
Technically the Small and Large Magellanic Clouds are seperate galaxies as well, (although they are orbiting the Milky Way) and they are just about the only other naked eye galaxies.

edit: There are 9 galaxies (outside the Milky Way) which can be seen with the naked eye, these are in order of distance;
Large Magellanic Cloud; 170,000 LY
Small Magellanic Cloud; 190,000 LY
Sculptor Galaxy; 300,000 LY
Leo I ; 600,000 LY
Leo II ; 600,000 LY
NGC6822; 1,800,000 LY
Wolf-Lundmark-Melotte; 2,000,000 LY
Andromeda; 2,200,000 LY
None of these can be mistaken for a star, they may be mistaken for Nebulae.

Answer 2

There are three galaxies that can be seen without optical aid (like a telescope or binoculars). They are: the Andromeda spiral (the subject of that article), the large and small Magellanic clouds (only visible from the southern hemisphere). Everything else that looks like a star and is seen without optics in the night sky is a star in our galaxy.

It was a major accomplishment of the last century to actually see individual stars in the Andromeda galaxy even with a telescope. With the scopes we have today, we can make out individual stars from several close galaxies, but it is a very delicate process.

Answer 3

As mentioned twice, the consensus for the star population of our Galaxy is a hundred thousand million! 100,000,000,000 or 10^11.

Googleplex is an interesting number, 10^100, and is larger than the total number of stars contained by all of the Galaxies in the universe!

Suppose that there are (as is accepted) a hundred thousand million galaxies like our Milky Way; suppose also that they hold the same number of stars as the MW, then we have 10^22 or so stars in total in the Universe! If you don't like my assumption about the number of stars in each galaxy, you can increase ten, hundred or a million times and still not get close to a googleplex.

Incidentally, "Googleplex" is also the name of the Google corporation's HQ.

The number of stars in the universe is finite.

Have fun counting...(wink!)
MM

Answer 4

OK people...wake up. Some people seem to think that the Sun is the only star in our galaxy. Have you not had you coffee?

Also, I saw two posts, one claiming that the number is infinite and the other that it is a googleplex.

Since nearly all the point sources of light in the night sky are stars in our galaxy (and a very small proportion at that, and since the number of stars in our galaxy is large but finite (2-4 hundred billion), then the number in the night sky is obviously not infinite or a googleplex.

Answer 5

Probably all the stars you see in the sky are in our galaxy, unless you have good eyes and are in a dark place.

There are a few things you can see that are extra galactic, the andomeda Galaxy for example can be seen with the naked eye, along with a few our galaxies.

The problem with things that are between galaxies is there is very little there and what is there is usualy very cold... so it doesn't shine.

All the naked eye stars in the sky are in our galaxy.

All the naked eye Nebulae in the sky are in our galaxy.

With a telescope you may be able, and it has to be quite a good telescope, to see a quasar or two, but again there are types of Galaxy.

So unless you have good eyes and can see Andromeda or a telescope, everything you can see in the sky is in our Galazy

Answer 6

All the stars that you can see in the night sky with the naked eye are in the Milky Way Galaxy. The only extra-galactic object that it is possible to see under ideal conditions (dark sky, no light pollution, no moon) is the Andromeda Galaxy that appears as a tiny fuzzy spot.

Answer 7

All the stars you see as points of light in the night sky are in in our galaxy. There are about 5,000 of them visible.

You will also see some blurs of light which you won't be able to distinguish as points of light:

The biggest blur is the Milky Way. It is the main part of our galaxy and has about 100,000,000,000 stars.

The small and large Magellanic clouds (in the southern hemisphere) are small satellite galaxies of our one, so they stars in them are not in our galaxy.

The M31 galaxy in Andromeda is a bigger galaxy than our own.

No other stars outside of our galaxy are visible to the naked eye.

Answer 8

All of the stars you can see with the naked eye are within our galaxy. It's possible though, with a telescope to see other galaxies such a Andromeda, but you can't pinpoint it's stars individually.

PS: To the guy who said that the universe was infinite - NO IT'S NOT!!!!!!

Answer 9

Depending on how dark the night sky is, most people can see approximately 2000 stars, all of which are in our galaxy.

Answer 10

All stars you can see are in our galaxy, with the exception of a few other naked eye galaxies, like Andromeda. Those are not actually stars but whole other galaxies made up of billions of stars themselves.