Carbon in Space
Date: 1999 - 2000
Why are we looking for carbon in outer space to determine
if life exists there? I know carbon composes all life on earth, but isn't
it at all possible for there to be a completely different set of elements
on other planets?
It's possible. We don't claim to know everything. However, the types of
molecules that make up living things - polymers such as proteins,
carbohydrates, and nucleic acids - all require large, well-defined
molecules. So far, all types of chemical "functional groups" we know of
that canform such molecules contain carbon. The only element that even
comes close is silicon, but silicon-containing polymers do not have the
broad range of chemical reactivity as carbon-containing compounds. In
fact, basically all of the silicon-containing polymers known that behave as
discrete molecules (as opposed to being rocks) contain about twice as many
carbon atoms as silicon atoms.
Richard Barrans Jr., Ph.D.
Click here to return to the Astronomy Archives
Update: June 2012