The only place in the Universe where we know life exists is on Earth. However, with billions of other star systems in the universe, it may not be the best place for life. In a new study, astronomers modeled the potential for life on other watery planets and discovered some conditions that can create oceans that are optimal for habitability.
The model suggests that watery planets with dense atmospheres, continents, and long days — planets that rotate slowly — were the most suitable for life. These conditions increase ocean circulation, which brings nutrients from the depths to the surface, where they can be used by organisms.
“[The research] shows us that conditions on some exoplanets with favorable ocean circulation patterns could be better suited to support life that is more abundant or more active than life on Earth,” Stephanie Olson, a University of Chicago researcher who lead the new study, said in a press release.
Over 4,000 exoplanets have been confirmed to date, with a small number of those worlds orbiting at a safe enough distance from their host star to have liquid water on their surfaces. These habitable zone planets are at the forefront of the search for alien life, and the new findings, presented at the Goldschmidt Conference in Barcelona, Spain, will help astronomers in narrowing their search.
Previous studies on exoplanet habitability largely ignored the role of oceans in regulating global climate and heat transport. The researchers focused on this niche, using a computer model to compare various climates and ocean habitats that could exist on exoplanets throughout the galaxy. The study aimed to look for things like upwelling, a type of wind-driven ocean circulation.
Upwelling and ocean circulation have long been important in maintaining life in the Earth’s oceans. Because the oceans and atmospheres are inextricably linked, the evolution of life in the oceans has been reflected in chemical changes in the atmosphere. Although astronomers are unlikely to see life on other planets directly, seeing these so-called biosignatures in exoplanet atmospheres may be possible with the next generation of telescopes. Finally, this research will help scientists in selecting the best candidates for further study from the growing list of exoplanets.
“One of the things we don’t really understand particularly well in the exoplanet community is how oceans on some of these planets might be working,” said Chris Reinhard, professor at the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology, who was not involved in the new study. “Part of that is because we haven’t had the computer models or people working on them to really explore these things, so there’s a lot to learn. This is a really huge step in the right direction to figure some of those things out.”