Earth and the rest of our solar system's inner, rocky planets are the products of a myriad of tiny planetesimals — glorified pebbles of primordial cosmic dust — assembling themselves together more than 4 billion years ago. Now, a new analysis suggests that those planetesimals already contained water.
Researchers tested samples from meteorites that they say are just as ancient as those planetesimals. In doing so, they found the fingerprints of chemical reactions known to occur in the presence of water.
