a temperate exoplanet 40 light years from Earth

Astronomers have made an exciting discovery: an Earth-like exoplanet located just 40 light-years away. Named Gliese 12 b, this world has characteristics that could make it habitable and is therefore generating considerable interest in the scientific community.

A temperate planet

Gliese 12 b orbits its host star, a red dwarf called Gliese 12in just 12.8 days. Its size is comparable to that of Venusslightly smaller than Earth. What sets it apart is its surface temperature estimated at 42°Ca value lower than that of most of the 5,000 exoplanets confirmed to date. This temperature was calculated assuming that the planet has no atmosphere. Determining whether Gliese 12 b has an atmosphere will be crucial, however. An “Earthly” atmosphere could indeed maintain temperatures favorable to liquid water and potentially life. Conversely, an atmosphere similar to that of Venus, where the greenhouse effect has led to hellish temperatures of 400°C, would considerably reduce its chances of being habitable. Alternatively, the planet could have an atmosphere completely different from those known in our Solar System.
This illustration compares Earth with different possible interpretations of Gliese 12 b, from an atmosphereless atmosphere to a thick atmosphere similar to that of Venus. Credits: NASA/JPL-Caltech/R. Blessé (Caltech-IPAC)

Research and exploration potential

Although Gliese 12 b is not the first Earth-like exoplanet discovered, it is notable for its relative proximity and its favorable conditions for in-depth study. For comparison, Proxima Centauri b is the closest planet to us, located just four light-years away. However, the lack of transits makes it difficult to study its atmosphere and its potential to support life. In other words, from our perspective on Earth, Proxima Centauri b does not pass in front of its host star, Proxima Centauri, preventing astronomers from using the transit method to collect detailed data. In contrast, as a transiting planet, Gliese 12 b offers a valuable opportunity to examine its atmospheric characteristics using this method. Researchers estimate as well as its moderate temperature and similar size to Earth, this planet is an ideal target for future studies, particularly with James Webb Space Telescope. By studying this exoplanet, scientists hope to gain crucial clues about the conditions necessary for life. By analyzing Gliese 12 b’s atmosphere, researchers will also be able to compare its evolution to that of Earth and Venus. This could help to understand why these two planets, although similar in some ways, have evolved so differently. This research could also reveal how planetary atmospheres form and evolve, and what conditions are needed to sustain liquid water, an essential element for life.