Life in the early universe might have formed on carbon planets made of carbides, graphite, and diamond, according to a study accepted for publication and is available online in the Monthly Notices of the Royal Astronomical Society. The study’s researchers from Harvard University claim this indicates that even planets that contain minute amounts of carbon can still support life.

“This work shows that even stars with a tiny fraction of the carbon in our solar system can host planets,” adds the study’s lead author Natalie Mashian, a graduate student from Harvard University. “We have good reason to believe that alien life will be carbon-based, like life on Earth, so this also bodes well for the possibility of life in the early universe.”

The research team suggests that ancient CEMP stars or carbon-enhanced metal-poor stars, formed before heavy metals crucial for life on Earth, were spread throughout the universe that influenced planet formation by clumping carbon dust grains together to form carbon planets. Although these planets would be considered as tar-black worlds with the same size and mass as other Earth-like worlds, these are still capable of sustaining life.

carbon planets

Artist’s concept of Earth vs 55 Cancri e, which mass could be in the form of diamond. Credit: NASA/JPL-Caltech/R. Hurt (SSC)

“These stars are fossils from the young universe,” says Mashian’s Ph.D. thesis advisor Avi Loeb from the Harvard-Smithsonian Center for Astrophysics. “By studying them, we can look at how planets, and possibly life in the universe, got started.”

If this theory turns out to be true, astronomers still need to assess the tar-black planets’ atmosphere to determine other details they do not know about. However, they think that the planets’ atmosphere contain huge amounts of methane and carbon dioxide.

Finding these planets could be possible using the transit technique. This technique is the same method used by scientists to detect other exoplanets, which Loeb asserts is a practical method for analyzing how early planets could have formed during the universe’s infancy.