There are approximately 100 thousand million stars in the Milky Way.

 

There are approximately 100 thousand million stars in the Milky Way.

Out of all the known galaxies, the Milky Way is the one that contains the most stars.

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 quantities like the number and luminosity of galaxies. ESA's infrared space observatory Herschel has made an important contribution by 'counting' galaxies in the infrared, and measuring their luminosity in this range – something never before attempted.