Can anyone tell me how many stars there are?

Question

We know that it's a LOT, because we can see with our eyes and our lovely telescopes that there are, because we have actually counted and catalogued them. My question is, how do you count the ones you cannot see?

You know without a doubt, there's more, but how do you really really know if you can't see them?
What is the thought process that leads to the conclusion that the unseen, unverifiable star is real? Is it The Scientific Method? Please help me understand the manner in which Science comes to it's conclusions.

so the answer is No. Nobody can say how many?
Why not? Because we lack the faculties to count them? NO. We can count them if we could only see them, but at this point in our existence and this stage of our technology, we can not see them all to count them all. If we continue to count the ones we see and continue to expand our abilities to see them and continue to count.......at some point.....we wil, indeed, have seen them all and counted them all.

Does this theory work? Why or why not?

Answer 1

The number of stars will NEVER be the same at anytime, therefore a real count in never going to be made. A start can burn out or another one may apear, thus the number is always changing, and we wouldn't be able to count but maybe 1/100 of what is out there. We have no idea how large " space " really is, and don't know the stars from there either, so the closet anyone will ever get is saying there are billions and billions..and they are right..its an estimated guess, and thats about as close as we can come at this point.

Answer 2

About 5*10^22, as a rough estimation.

Let us see how this figure is derived:

10^9 is an essay on the number of galaxies and the number of stars within galaxies.

For purposes of calculating the totality of all stars, it is assumed that our galaxy is an average size galaxy and that there are about 500 billion galaxies in total in the universe. Multiplying the two gives on the order of 5 x 10^22 for the total number of stars in the universe.

That conclusion is helped by observation and astronomical theories too. Our own Galaxy, the Milky Way, is not too different from the others observed, as a mean. With the current powerful telescopes sky has been observed up to 13,400 light-year deep, in which limits of time and distance no galaxies were formed. So we can conclude that we have observed the complete volume occupied by galaxies in our universe. As we can estimate the number of stars in our galaxy, and we can also estimate the number of galaxies in the universe, we can obtain a figure (it is just an approximation, of course).

Observation: The number of stars is not infinite. Were it so, the night sky will be as bright as a sunny day, according to what is known as "Olbers paradox", due to the summing up of the light of all stars. On the other hand, when we observe the deep sky, this is equivalent to travel to the past in a time machine, for light from those parts of the universe lasted billions of years to reach us. According to the very well established Big-Bang theory, we have reached the limit of 300 million years after the big-bang, when galaxies were still to be formed, and the universe was formed still by energy and elemental particles. That mean that we have observed, thanks to telescopes like Hubble, all the volume of the Universe containing galaxies, so we are able to figure out the approximate number of galaxies and stars.

Answer 3

You can't count them directly, but you can make reasonable estimates.

First, you need to estimate the number of stars within our own galaxy. We can do that by first estimating the size of the galaxy, and then the density of stars in our own neighborhood. We know that the Milky Way is a large spiral galaxy, and we have good reason to believe that it is about the same size and shape as the Andromeda Galaxy (M31) which is close by. This leads us to estimate that the Milky Way is about 100,000 light-years in diameter. Its thickness in the center is about 20,000 light-years, but out here in the spiral arms its only 2,000 light-years thick.

Knowing that, we compute the volume of the Milky Way: 1.5 x 10^13 cubic light-years for the disk. If we can figure the density of stars, we can then estimate the number of stars in the Galaxy.

Around here, we can determine by direct observation that the average distance from one star to the next is about 4 light years. So the density of stars where we are is about 1 star for every 64 cubic light-years, which implies that the total number of stars in the disk would be about 200 billion. However, the disk is not uniform; by looking at other galaxies, it is clear that some parts of the disk should have a lot of stars and some parts a lot less. So to be conservative, we'll divide that number by 2, and estimate that the number of stars in the disk is about 100 billion.

Using similar techniques, we can also estimate that the number of stars in the central bulge is also about 100 billion or so, meaning that the total number of stars in the Milky Way is (very roughly) 200 billion.

Then, by photographing a small section of the sky at very long exposure times, we can see very dim galaxies at great distances. You can take one of these "deep" photos, count the galaxies, and multiply by the fraction of the sky in the photo, to get a reasonable estimate of the total number of galaxies we can see in the universe. That number comes out to about 100 billion as well.

So there are 100 billion galaxies, and the average galaxy has about 100 billion stars (because, as it turns out, the Milky Way is a larger-than-average galaxy). That implies that the total number of stars in the observable universe is something like 10^22.

Answer 4

It comes in Space Science. We can find stars which are not viewable with our naked eyes by methods like sending out radio waves which bounce back after hitting anything in the space.
NASA had sent a radio wave in 2004 to the constellation of Hercules. And how many stars are there? There might be billions and trillions of stars in the whole universe. But no living (or dead!!!) person knows how many stars are there in our universe. And also, the universe never ends, thus we cannot count the number of stars in our universe.

Answer 5

Have you ever looked up into the night sky and wondered just how many stars there are in space? This question has fascinated scientists as well as philosophers, musicians and dreamers throughout the ages.

Look into the sky on a clear night, out of the glare of streetlights, and you will see a few thousand individual stars with your naked eyes. With even a modest amateur telescope, millions more will come into view.

So how many stars are there in the Universe? It is easy to ask this question, but difficult for scientists to give a fair answer!

Stars are not scattered randomly through space, they are gathered together into vast groups known as galaxies. The Sun belongs to a galaxy called the Milky Way. Astronomers estimate there are about 100 thousand million stars in the Milky Way alone. Outside that, there are millions upon millions of other galaxies also!



Nearby galaxy NGC 1569

Hipparcos mapped millions of stars in our galaxy, but how many more are there?
It has been said that counting the stars in the Universe is like trying to count the number of sand grains on a beach on Earth. We might do that by measuring the surface area of the beach, and determining the average depth of the sand layer.

If we count the number of grains in a small representative volume of sand, by multiplication we can estimate the number of grains on the whole beach.

For the Universe, the galaxies are our small representative volumes, and there are something like 1011 to 1012 stars in our galaxy, and there are perhaps something like 1011 or 1012 galaxies.

With this simple calculation you get something like 1022 to 1024 stars in the Universe. This is only a rough number, as obviously not all galaxies are the same, just like on a beach the depth of sand will not be the same in different places.

No one would try to count stars individually, instead we measure integrated quantitites like the number and luminosity of galaxies. ESA's infrared space observatory Herschel, to be launched in 2007, will make an important contribution by 'counting' galaxies in the infrared, and measuring their luminosity in this range - something never before attempted.

Knowing how fast stars form can bring more certainty to calculations. Herschel will also chart the 'formation rate' of stars throughout cosmic history. If you can estimate the rate at which stars have formed, you will be able to estimate how many stars there are in the Universe today.



Herschel's telescope

Herschel's telescope will collect infrared radiation from distant stars
In 1995, an image from the Hubble Space Telescope (HST) suggested that star formation had reached a peak at roughly seven thousand million years ago. Recently, however, astronomers have thought again.

The Hubble Deep Field image was taken at optical wavelengths and there is now some evidence that a lot of early star formation was hidden by thick dust clouds. Dust clouds block the stars from view and convert their light into infrared radiation, making them invisible to the HST.

Herschel is designed to view exactly the time in the evolution of the Universe, at the right wavelengths where it is thought the majority of the obscured star formation can be seen.

So with Herschel, astronomers will see many more stars than before. We will be one step closer to provide a more reliable estimate to that question asked so often in the past - "How many stars are there?"


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Answer 6

the truth is, nobody really knows.im taking college astronomy and my teacher said there are billions and billions, but no way of really counting.

we are just in the milky way galaxy...there are BILLIONS of other galaxies..with stars in them too!

just think about counting every blade of grass or every piece of sand on earth--its just not possible

they know because they have probes they send out and huge telescopes that can see very far that both take pictures

we cant even travel to mars yet so its really hard to know for sure

Answer 7

The universe never ends, therefore the number of stars is infinite.

Answer 8

there are more stars in the universe than there are grains of sand on all the beaches in the world

Answer 9

there is diffinite count on stars. the number of stars in our universe is exactly equal to the number of sand grains in our beaches and under the sea.

Answer 10

noone can tell you.

theyve only counted and catalogged the ones seen.

how do you know theres more? how do you know a fallnig tree makes a sound if theres noone there to hear it?