Astronomers have observed a pair of exoplanets about 100 light-years from Earth, and they say one, which has never been seen before, is a strong candidate for supporting life.
“The outer planet is in the inner edge of what is called the habitable zone, a bit like the Earth is,” Amaury Triaud, who studies exoplanets at the University of Birmingham in the United Kingdom and is a member of the team who made the discovery, tells New Scientist’s Alex Wilkins.
A planet in a star’s habitable zone could have the conditions necessary for liquid water to exist on its surface. Of all the exoplanets discovered in habitable zones so far, this one, Triaud tells New Scientist, is the second-best candidate for hosting life, by his calculations.
The team details their findings in a forthcoming paper in the journal Astronomy & Astrophysics.
The promising planet is about 40% larger than Earth and orbits its star roughly once every 8.5 days, according to a press release. Based on its size, “we expect the planet to be rocky,” Laetitia Delrez, lead of author of the paper and an astronomer at the University of Liège in Belgium, tells Inverse’s Kiona Smith. “We have not yet found exoplanets as small as 1.4 Earth radii that are not rocky.”
Delrez tells Inverse that the planet is also probably tidally locked to its star, meaning that it's always daytime on one side and always night on the other. It’s only 3.7 million miles from its sun, while Earth orbits 93 million miles from ours, writes NPR’s Dustin Jones.
Despite its proximity to the star it orbits, the exoplanet could still have suitable conditions for life, says Francisco J. Pozuelos, a co-author of the paper and a researcher at the Institute of Astrophysics of Andalusia in Spain, in the press release. That’s because the planet’s sun is only half the temperature of ours, and it’s roughly 6.5 times smaller.
Still, some traits might work against the planet’s potential habitability: It is larger than Earth, and it might be receiving a high level of radiation from orbiting close to its star, which are both points against it hosting life, Beth Biller, an astronomer at the University of Edinburgh in the U.K. who did not contribute to the research, tells New Scientist.
To discover the exoplanet, the researchers used telescopes from a project called SPECULOOS—or, Search for habitable Planets EClipsing ULtra-cOOl Stars. First, they observed this distant solar system and confirmed the existence of another planet in it, which had first been spotted by NASA’s Transiting Exoplanet Survey, or TESS, according to Inverse. That planet was too close to its star to support life, but by continuing the search, they revealed the second, more promising planet, Inverse reports.
TESS spots planets by measuring stars’ light levels. When a planet passes between a star and the satellite, TESS can detect the starlight dimming, writes NPR. Then, the ground-based SPECULOOS telescopes, which have a stronger sensitivity to infrared light, follow up to confirm the find. This second look is necessary because cold stars, like the one orbited by the newly discovered planet, emit mostly infrared light, according to Space.com’s Robert Lea.
Next, the scientists hope to use the James Webb Space Telescope to find out what makes up the planet’s atmosphere—if it even has one at all. By using Webb, researchers could learn more about the exoplanet’s potential for hosting life, per Inverse.