Potential Super-Earth May Have Just Been Discovered Orbiting Nearest Star to the Sun

The planet is part of the Proxima Centauri planetary system.
Fabienne Lang
Illustration of Proxima Centauri planetary systemLorenzo Santinelli/INAF

According to astronomers, the star that's closest to our sun may have a second planet orbiting in its system — and it may be a super-Earth. 

The Proxima Centauri is our closest neighboring star, a mere 4.2 light-years away. It already has one planet that's known to astronomers, the Proxima b. Now, scientists from Italy's National Institute for Astrophysics say that changes in the star's activity could indicate a second orbiting planet.

Their study was published in the journal Science Advances on Wednesday. 


What is a super-Earth?

A planet deemed a super-Earth is one that has a mass larger than our Earth but is quite a bit smaller than icy Neptune. 

Astronomer and lead author of the paper, Mario Damasso, told Business Insider that the "Proxima Centauri is the nearest star to the sun, and this detection would make it the closest planetary system to us." 

Proxima c, as the new super-Earth has been dubbed, is most likely unhabitable given its location to its star. If it exists at all, it is probably covered in ice or a suffocating hydrogen-helium environment. 

But if it does indeed exist, its proximity to us could offer a fantastic opportunity to observe another star system. 

Illustration of Earth-sized planets in space. Source: R. Hurt/NASA-JPL Caltech

Why is Proxima c not confirmed?

Typically, super-Earths form around the "snowline" — the distance to a star where water turns to ice. Proxima c, however, is beyond that snowline. 

If it does exist, it could force astronomers to rethink their theory. However, it may also mean that it simply doesn't exist. 

The reason astronomers think they've found Proxima c is because the color of the light of its star changed. This is because its star will have shifted positions — usually a sign that there is a planet tugging on the star as it orbits. 

Damasso carefully stated that they "cannot discard the possibility that the signal is actually due to the activity of the star."

The Gaia space telescope, Source: ESA

Further research will continue with the use of ESA's Gaia space telescope. NASA's upcoming James Webb Space Telescope due to launch in March 2021 may also be useful in answering some of the researchers' questions.