A team of Harvard astronomers led by Li Zeng has recently showed that extrasolar planets which are between 2 to 4 times larger than Earth might have a large water percentage on their surface. These findings were shared during the Goldschmidt 2018 conference in Boston, Massachusets which took place on the 17th of August.
It was in 1992 that exoplanets were found orbiting around other stars. Since then, there was an increased interest in finding out what these planets were made of and whether they were able of sustaining life or not.
The Kepler Space Telescope from NASA teamed up with ESA’s Gaia satellite to provide new data to be analyzed. It seems that there are a lot of extrasolar planets which contain more than 50% water. This is incredible when we compare it to our Earth, which has only 0.02% water (when we consider its weight).
Dr Zeng stated how surprising it was to find out that such water-worlds exist and in such a big number too. So far, 4000 confirmed or candidate exoplanets were discovered. Many of them fall into one of two categories. Both are compared to Earth: the first one includes a planetary radius 1.5 bigger than the Earths, while for the second one a 2.5 degree of comparison was used.
This team of scientists concluded that the first category consists of mostly rocky planets while the second one is filled with water-worlds. While water is definitely there, don’t expect it to be as it is present here, on our planet. That’s because the temperature on these planets varies between 200 to 500 degrees Celsius.
This means that water is mostly present in its gaseous state, only a thin liquid layer being present on their surface. Deeper into the planet we would find high-pressure ice formations before we come across the planet’s core.