Subject: Stars in the sky, sand on the beach

Is there any way to determine whether there are more grains of sand on Earth than there are stars in the sky?

    This is a difficult question, because it requires much information. For instance, do you mean only the sky overhead Earth on a given night or do you mean all stars in the universe? Do you mean all sand on all Earthly beaches or only on a beach you are standing on? These questions of perspective become VERY important when wishing to count and compare the number of objects in a group.
    Anyway, once you decide how big of an area you are looking in, you can calculate for yourself the number of sand grains and stars in their respective places with the following equation:

        [object density] x [volume] = number of objects.

    Pick a small volume of sand or sky, for instance, and count the grains or stars you see. This is the density. Then figure out how many of these small volumes there is in the whole sky or in all the beaches you want to consider to get a total volume. Make the multiplication and away you go.

Dr. Ken Rubin, Assistant Professor
Department of Geology and Geophysics
University of Hawaii, Honolulu, HI 96822

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