system
Given the following post, respond as if you're commenting on Reddit:
human
In one of his older short stories, one of Clarke's characters says about a comet's tail: "A volume as big as Earth contains about as much gas as a matchbox full of air." Is this correct?
gpt
There are 2.69\*10\^25 molecules in one cubic meter of air at sea level. A match box is about 15 cubic cm.  There are 1\*10\^6 cubic cm in a cubic m.  So there are about 2.69\*10\^19 molecules in a match box at sea-level pressure.

The volume of the earth is about 1.083207×10\^21 cubic meters.  There is a density of interplanetary space of about 5 particles per cubic cm.  This means there is already 5.416035\*10\^27 particles in the volume of the earth.

The volume of the earth in interplanetary space would already have about 100 million times the number of molecules as the matchbox of air.

I'd say he's exaggerating.  That said, the density of a comet tail is very, very, very low.  There isn't that much material in it considering it's all boiling off of a nucleus perhaps a few miles across and has been doing so for centuries.