# Are there more stars in the universe than grains of sand in the Earth?

My ten year old daughter asked me this question at breakfast and I initially said yes, but on second thought I was also puzzled.

• On Skeptics.SE: skeptics.stackexchange.com/questions/9059/… – Andrew Grimm Nov 13 '17 at 4:05
• From @AndrewGrimm 's link, 10^20 to 10^24 grains of sand, 7x10^22 stars. You can shrug and tell her "dunno" ;) – JollyJoker Nov 13 '17 at 8:48
• @JollyJoker about a mole of each. – Andrew Grimm Nov 13 '17 at 9:22
• According to Neil deGrasse Tyson, there are indeed. And if it's good enough for Neil deGrasse Tyson, it's good enough for me. – roberto06 Nov 13 '17 at 14:18
• The estimates of each quantity are so plentiful as to vie with the answers themselves in magnitude. – Carl Witthoft Nov 13 '17 at 15:57

A quick google gave me these (approximate) figures:

• 7.5 x 1018 grains of sand in all the beaches and deserts of the world

• 7 x 1022 stars in the observable universe

If these are reasonable estimates, then there are approximately nine thousand stars in the observable universe for each grain of sand on Earth. (By observable universe, I mean in all the galaxies that we can detect with our most powerful telescopes.)

Robert Krulwich: Which Is Greater, The Number Of Sand Grains On Earth Or Stars In The Sky?

• How much sand is there in all the other places? ;-) – Dronz Nov 13 '17 at 0:28
• Nitpick: the observable universe has nothing to do with telescopes. Merely whether EMR emitted from the source after the recombination epoch has had sufficient time to reach Earth. Whether or not we can detect it is irrelevant (ironically enough.) – corsiKa Nov 13 '17 at 3:30
• The number you've quoted is all the grains of sand on beaches. Presumably the number of grains of sand in all the world (including under the sea) would be dramatically larger given that beaches and deserts represent less than a tiny fraction of the area of the ocean. – Valorum Nov 13 '17 at 7:25
• @Valorum Beaches and deserts. And doing some Googling, it seems the ocean floor is mostly rocky, not sandy. Only coastlines are sandy, and they were hopefull included in the calculation. – Erwin Bolwidt Nov 13 '17 at 9:09
• Since the calculations only use visible beaches, I'd imagine that the number is out by at least 100% even if you only account for the sand a few miles offshore. – Valorum Nov 13 '17 at 12:16