A massive “super-Earth” exoplanet, located in one of the closest star systems to ours, could be much more favorable to extraterrestrial life than scientists previously thought. According to a recent study relayed by Live Science, its proximity to Earth and the characteristics of its star make it an ideal target for future observations.
This planet, named GJ 3378b, was discovered in 2024 and orbits a red dwarf star located about 25 light years from Earth. Its orbit is very fast, making a complete revolution in just 21.5 days, at a distance approximately ten times closer to its star than the Earth is to the Sun.
In our solar system, such proximity would make the planet completely uninhabitable. However, its star emits about 90% less radiation than the Sun. Thanks to this low light, GJ 3378b is in the heart of the “habitable zone”, a region where conditions could allow the presence of liquid water on the surface.
At the time of its discovery, researchers estimated that the planet was about five times more massive than Earth. If it were rocky, it would have been classified as a super-Earth, a category often considered favorable for the appearance of life. However, uncertainties remained: it was difficult to determine whether GJ 3378b had a solid surface or whether it was more of a small gas giant.
Even assuming a rocky planet, its supposed mass suggested that its atmospheric pressure would be extremely high, making conditions unfavorable for life. This uncertainty therefore limited its interest as a potential candidate for habitability.
Not that big
A new study, published at the end of June in The Astrophysical Journal, made it possible to review these estimates. Using a specialized instrument capable of measuring the star’s tiny wobbles caused by the gravity of its planets, the researchers precisely recalculated the mass and orbit of GJ 3378b.
The results are encouraging: the planet is in reality only 2.3 times more massive than Earth. This more moderate size strongly reinforces the hypothesis of a rocky world and suggests that it could have an atmosphere with a pressure comparable to that of our planet, thus increasing the chances of finding conditions favorable to life there.
Despite this optimism, major unknowns remain. There is no evidence yet that GJ 3378b has an atmosphere or liquid water. Its proximity to its star could have led to the disappearance of its gaseous envelope under the effect of stellar winds, a phenomenon similar to that which would have deprived Mars of its atmosphere and its ancient oceans.
However, its relative proximity to Earth makes it a prime target for future observations. If the presence of an atmosphere were to be confirmed, GJ 3378b could quickly become one of the most promising exoplanets in the search for signs of life, especially since it orbits a red dwarf, the most common type of star in the Milky Way.
