Shared from Science and Belief, a snippet, great piece.
Water is a strange thing. The unique structure of its molecules allow it take on three different forms: a liquid that is easily absorbed into porous substances (i.e. it’s wet!), ice that floats, and a gas. In the bookWater and Life: The Unique Properties of H2O, the biophysicist Felix Franks has contributed a chapter explaining some of these properties, and how they may have played a part in the origin of life.
The chemistry of life has adapted to water and become very dependent on it, so that even ‘heavy water’[i] is toxic in large doses[ii]. But where did water come from in the first place? No one is completely sure, but HO (as opposed to H2) seems to be the most common chemical in space after hydrogen. Water is present on the interstellar dust particles that come together to form comets. There is solid water in cold stars and meteorites, and signs of some sort of water have even been detected in the sun.