A Southwest Research Institute-led study modeled the chemistry of TOI-270 d, an exoplanet between Earth and Neptune in size, finding evidence that it could be a giant rocky planet shrouded in a thick, hot atmosphere. TOI-270 d is only 73 light years from Earth and could serve as a “Rosetta Stone” for understanding an entire class of new planets.

Exoplanets orbit stars outside of our solar system. Sub-Neptunes refer to planets between the size of our solar system’s largest rocky planet, Earth, and the smallest gas giant, Neptune.

“The nature of sub-Neptunes is one of the hottest topics in exoplanetary science,” said SwRI’s Dr. Christopher Glein, first author of a paper accepted for publication in the Astrophysical Journal and available on the preprint server arXiv.