When NASA's New Horizons spacecraft sped by Pluto in 2015, it revealed an incredible world of ice and haze carved by various geological processes — hinting that an ocean may have played a role in the ...

"'Oumuamua is in a different category of object. It's much harder to find, but there are a lot more of them." The first interstellar object to visit the solar system may have been a fragment of an icy ...