Comparison of the liquid water volume of Earth, Europa, and Titan to scale. It is estimated that Europa has over two times  and Titan nearly eleven times more liquid water as subsurface oceans than Earth. If most of the water in the Solar System originated inside interstellar molecular clouds as Cleeves team's study suggest, then potentially habitable worlds like Europa and Titan might also exist on other planetary systems as well. Image Credit: PHL @ UPR Arecibo, NASA