Ask A Scientist© Astronomy Archive

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


Answer:  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. Th e 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'm not sure
whether better estimates of both numbers would give more stars, or more sand
grains - there's a lot of both!
Asmith