Scientists discover planets that likely have more water than Earth out there

These are the planets Kepler-138 c and Kepler-138 d. It is about three times the size of Earth and weighs twice as much. The planets orbit the star Kepler-138, 218 light-years from Earth. The galaxy was discovered in 2014 and is now being studied with the Hubble and Spitzer space telescopes. The research was published Thursday in the scientific journal natural astronomy.

Scientists have never seen the water itself. The planets are very far away from that. Measurements made by the researchers show that it is primarily composed of matter that is lighter than rock, but heavier than gases such as hydrogen or helium.

The Earth is rocky, but gas giants like Jupiter are composed primarily of gas. Researchers believe that water is the more likely choice of the two. “This is the best evidence for water planets to date. Astronomers have long believed that this type of planet must exist.”

If there is indeed a lot of water on the two planets, this does not mean that they are Earth-like. For example, they do not need oceans, waterfalls and precipitation, as scientists assure.

Nor is it certain whether life is possible there. “The temperature in Kepler-138d’s atmosphere is likely to be above the boiling point of water. The planet likely has a thick, dense atmosphere of vapor. Below that, water could be under high pressure, perhaps somewhere between a liquid and a gaseous.”