Long-Lasting Oceans Mean ET May Be Found on Super-Earths

A new study suggests that extragalactic super-Earths may contain the same eon-spanning oceans that helped catalyze the birth and evolution of life on Earth.

Scientific consensus holds that water is vital for life and its evolution. Fortunately for all terrestrials our planet’s oceans have been around for several billion years, allowing H2O to catalyze an explosion of biological complexity.

In the earliest epochs of Earth’s life countless numbers of asteroids and comets pelted our planet with solid rocky material and water ices from the outer solar system. Over millions of years the accumulation of alien ices grew to flood the titanic gulfs surrounding our continents while also depositing vast volumes of water in our planet’s mantle. In fact, because of the constant subduction of Earth’s tectonic plates entire oceans lie beneath the seafloor waiting to be returned to the global water table by deep-sea volcanos and mid-ocean ridges.

With that geologic history in mind Laura Schaefer, astronomer at Harvard-Smithsonian Center for Astrophysics, began to run computer simulations to see if these same factors would shape how oceans behave on Earth-like planets up to 5 times more massive than Earth.

Detailed in her survey, Schaefer found that super-Earth’s between 2-4 times the mass of Earth would be able to establish and maintain their oceans better than our planet and possibly keep them vital for up to 10B years. However, once extraterrestrial worlds grew outside of that range the ability for them to jumpstart oceanic growth was hindered by size.

In the end, Schaefer’s research may shape the direction of our search for extraterrestrial life. "This [study] suggests that if you want to look for life, you should look at older super-Earths," said Schaefer.

Given what we now think we know about worlds beyond the Milky Way, exoplanet hunters and SETI technicians might do well to look to the oceans as their guide for life. Then again, with how little we know about our own planet’s aquatic inhabitants we might also consider peering into the local deep-blue to find life that’s equally alien right here at home.

Image Courtesy of Harvard-Smithsonian Center for Astrophysics