Exoplanet Waterworlds Could Support Life

The conditions for life surviving on planets entirely covered in water are more fluid than previously thought, opening up the possibility that water worlds could be habitable, according to a new paper from the University of Chicago and Pennsylvania State University.

The scientific community has largely assumed that planets covered in a deep ocean would not support the cycling of minerals and gases that keeps the climate stable on Earth, and thus wouldn’t be friendly to life. But the study, published Aug. 30 in The Astrophysical Journal, found that ocean planets could stay in the “sweet spot” for habitability much longer than previously assumed. The authors based their findings on more than a thousand simulations.

“This really pushes back against the idea you need an Earth clone–that is, a planet with some land and a shallow ocean,” said Edwin Kite, assistant professor of geophysical sciences at UChicago and lead author of the study.

As telescopes get better, scientists are finding more and more planets orbiting stars in other solar systems. Such discoveries are resulting in new research into how life could potentially survive on other planets, some of which are very different from Earth–some may be covered entirely in water hundreds of miles deep.

Because life needs an extended period to evolve, and because the light and heat on planets can change as their stars age, scientists usually look for planets that have both some water and some way to keep their climates stable over time. The primary method we know of is how Earth does it. Over long timescales, our planet cools itself by drawing down greenhouse gases into minerals and warms itself up by releasing them via volcanoes.

GJ1214b, shown in this artist’s view, is a super-Earth orbiting a red dwarf star 40 light-years from Earth. New observations from NASA’s Hubble Space Telescope show that it is a waterworld enshrouded by a thick, steamy atmosphere. GJ1214b represents a new type of planet, like nothing seen in our solar system or any other planetary system currently known.