Ask A Scientist© Astronomy Archive

Author:      m french
Are there more stars or are there more grains of sand?

Response #:  1 of 1
Author:      asmith
Well, if every star came with a planet like Earth that had billions of sand
grains, there would have to be more sand grains than stars!  The number of
stars in our galaxy is around 100 billion or 10^11 in exponential notation. 
The number of sand grains on earth is probably somewhere between 10^20 and
10^24.  The number of sand grains on Earth is therefore much greater than
the number of stars in our galaxy.  However, our galaxy is only one of about
100 billion in the visible universe, and so the total number of stars we
know about is around 10^22, which is kind of in the same ballpark as the
number of grains of sand on Earth.  Of course, those numbers are much bigger
than we can count - I am not sure whether better estimates of both numbers
would give more stars, or more sand grains - there is a lot of both!