Finding Water Worlds

Sep 3, 2018


Credit Nicolas Thomas / unsplash

In recent weeks we’ve seen headlines proclaiming water on Mars and the moon. We tend to think of water - whether it's liquid or ice - as being relatively rare in our solar system. But what if the universe were full of watery worlds? That's what some new research is suggesting.


Li Zeng is the Simons Postdoctoral Fellow in the Department of Earth and Planetary Sciences at Harvard University, and he said that scientists are focusing their research on exoplanets. Simply put, exoplanets are planets orbiting around other stars, and it’s now believed that every star in the universe likely has its own planetary system.


Those exoplanets are where scientists are finding the likelihood of water. According to Zeng, observers measured the mass and radius of exoplanets and discovered that the density of the planets is consistent with a 50 percent water and 50 percent rock composition. By comparison, the Earth, which many people view as a watery planet, actually has way less than 1 percent of water weight.


"These other planets that you're talking about are in a totally different class. There are hundreds of times more water on these other planets than on this planet," Zeng said.


Another feature of note on these planets is the “snow line.” 


“Basically what it means is that the snow line is where the ice can form and condense into a solid face. Any planets that form beyond the snow line are expected to have a huge amount of ice,” Zeng said.


The findings are both a surprise and not a surprise Zeng said, because water is H2O. It's two hydrogen atoms plus one oxygen, and they’re very abundant elements. So when you combine the first abundant element with the third most abundant element you expect to find a lot of water in the universe. It's looking like it's not as rare as we thought.