The idea that comets delivered water to early Earth has fallen out of favor in the past decade, but a new look at data from the European Space Agency's (ESA) Rosetta mission to an iconic “rubber ducky” comet has reopened that possibility.
Water has a pretty simple chemical makeup: just three atoms (two hydrogen and one oxygen) in each molecule. It's also one of Earth's most abundant molecules, with our planet's oceans brimming with about a million trillion tons of the liquid.
