NASA Discovers Diamond Planets Made of Carbon May be Waterless and Lifeless

While some worlds have water, others don't. Now, scientists have discovered that so-called diamond planets made of carbon may lack oceans. The findings could aid researchers in their hunt for life on other planets as they scour the universe.

Our own star is a carbon-poor star. Because of this, Earth is largely made up of silicates rather than carbon. Stars with much more carbon than the sun, in contrast, can make planets that are mostly made of carbon with layers that are possibly composed of diamond. In order to find out if these planets would have water, though, the researchers turned to models.

The scientists modeled the ingredients in these carbon-based planetary systems. Surprisingly, they found that there was a lack of icy water reservoirs that are thought to supply planets with oceans. Extra carbon in developing star systems would actually snag oxygen, preventing it from forming water.

"The building blocks that went into making our oceans are the icy asteroids and comets," said Torrence Johnson, one of the researchers, in a news release. "If we keep track of these building blocks, we find that planets around carbon-rich stars come up dry."

The findings are huge when it comes to searching for life on exoplanets, which are planets beyond our solar system. Although scientists usually identify potentially habitable planets by whether or not they are situated within the "habitable zone" around their parent stars, the composition of these stars and the planets may also play a key role. If there is no water on a planet, then it's likely that there is also no life.

"It's ironic that if carbon, the main element of life, becomes too abundant, it will steal away the oxygen that would have made water, the solvent essential to life as we know it," said Jonathan Lunine, one of the collaborators on the research, in a news release.

The implications reveal a little bit more about how these diamond planets form and how unlikely they are to hosting life. This, in turn, could inform the future hunt for exoplanets.

"All rocky planets aren't created equal," said Lunine in a news release. "So-called diamond planets the size of Earth, if they exist, will look totally alien to us: lifeless, ocean-less desert worlds."

The findings are published in The Astrophysical Journal.