Ask Harley

How many stars can you see?

The number of stars you can see depends on how and where you are looking.

Within the universe, stars are grouped into galaxies and, to a lesser extent, into smaller globular clusters. As far as we know, there are billions of galaxies in the universe. In fact, nobody really knows how many there are.

In our galaxy, which is surrounded by a number of globular clusters, there are several hundred billion stars. The scientists using the Hubble Space Telescope have cataloged over 15 million of the brightest stars, but this is much more than we ourselves can see because (1) the Hubble is a lot more sensitive than our eyes, and (2) it is in orbit around the Earth, beyond the atmosphere. (On Earth, the atmosphere blocks a lot of the light from getting though.)

In principle, if you are on Earth looking out into the night sky without any special viewing aids (such as binoculars or telescopes), you could potentially see about 8,000 stars. However, all 8,000 stars are not visible from everywhere. What you see depends on where you are. It also depends on how good your eyes are, how clear the sky is, and how dark it is around you. Moreover, the longer you watch, the more different stars you will see, because as the Earth rotates, various stars come into and out of view.

In the Northern Hemisphere, if you are in a completely dark area on a completely clear night, you might be able to see about 1,500 stars with the naked eye. With sunglasses on, this number drops to about 7 (and even then you have to squint).