The small footprint and dim light of white dwarfs, remnants of stars that have burned through their fuel, may make excellent backdrops for studying planets with enough water to harbor life. The trick is spotting the shadow of a planet against a former star that has withered to a fraction of its size and finding that it’s a planet that has kept its water oceans for billions of years even after riding out the star’s explosive and violent final throes. A new study of the dynamics of white dwarf systems suggests that, in theory, some watery planets may indeed thread the celestial needles necessary to await discovery and closer scrutiny.
