Here's how water world could support life

Water world 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 keep the climate stable on Earth, and thus wouldn't be friendly to life.

The study 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.

Lead author of the study Edwin Kite, said, "This really pushes back against the idea you need an Earth clone--that is, a planet with some land and a shallow ocean."

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.

This model, however, doesn't work on a water world, with deep water covering the rock and suppressing volcanoes.

Kite and Penn State coauthor Eric Ford wanted to know if there was another way. They set up a simulation with thousands of randomly generated planets, and tracked the evolution of their climates over billions of years.

"The surprise was that many of them stay stable for more than a billion years, just by luck of the draw," Kite said. "Our best guess is that it's on the order of 10 per cent of them."

The simulations assumed stars that are like our own, but the results are optimistic for red dwarf stars, too, Kite said. Planets in red dwarf systems are thought to be promising candidates for fostering life because these stars get brighter much more slowly than our sun--giving life a much longer time period to get started.

The full findings are present in the Astrophysical Journal.