Is it true that there are more stars in the universe than there are grains of sand on Earth How could one calculate such figures

Published: December 28, 2009

Stars outnumber grains of sand?

Photo by AURA/STScI/NASA

It's probably not true, yet we can't answer with certainty. But this question is a wonderful example of what we sometimes call a Fermi problem, after physicist Enrico Fermi, who asked the "big" questions. The key to solving them is that you don't need to know the answer to any decimal places at all. You can be wrong by a factor of 10 and that's close enough.

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	Sun	Sun	Moon
RISE	—		—	PHASE	—
SET	—		—	DISK	—

	Mercury	Mercury	Venus	Venus
RISE	—		—
SET	—		—
		—		—

	Mars	Mars	Jupiter	Jupiter	Saturn	Saturn
RISE	—		—		—
SET	—		—		—
		—		—		—