The Ark May Not Have Needed the Bad Science Comet

 ...because apparently water can just sit around in space.

Okay, not true. But they have found water in a protoplanetary disk. This indicates that the water on Earth may be older than our planet.

This will teach us something about how planets (and, of course, comets, which are snowballs) form. Comets are made up of leftover material, which might include water, that can then be deposited on the planets.