In our search for life beyond our own little corner of the cosmos, it's a really good idea to look for water. No life we know of exists without it.
So when astronomers go looking at planets orbiting stars outside of our Solar System, discovering water is a positive sign. New research presented at the Goldschmidt geochemical conference in Boston on Friday suggests that water worlds may be a lot more common than we had believed.
The team of researchers at Harvard University, led by Dr. Li Zeng, analyzed data from the Kepler Space Telescope, which has been planet-hunting since 2009. In that time, it has discovered more than 4000 exoplanets, most of which are regarded as Super-Earths, hulking planets that are 1.5 or 2.5 times the radius of Earth.
Using mass measurements from the European Space Agency's Gaia satellite, the team were able to predict the composition of these far-away planets
"We have looked at how mass relates to radius, and developed a model which might explain the relationship", Li Zeng said. That model suggests that around 35 percent of all currently known exoplanets that are bigger than Earth should be water worlds.
That's good news for Kevin Costner, of course, but it's also a positive for finding life. However, Zeng was quick to caution that while their model predicts these Super-Earths are filled with water, this isn't your everyday Terran water. This is water with a surface temperature well in excess of 200 degrees Celsius (around 392 degrees Fahrenheit).
Still, life finds a way.
"Life could develop in certain near-surface layers on these water worlds when the pressure, temperature and chemical conditions are appropriate," Zeng told Discover Magazine.
In the hunt for extraterrestrial life, water worlds certainly provide a handy start. NASA will get a further boost in its planet-hunting endeavors soon, with the Transiting Exoplanet Survey Satellite (TESS), which launched in April this year, ramping up its search in July. It's already snapped some stunning images of a comet zipping through space and now its focus is on finding new planets.
