Gliese 12b, an exoplanet just 40 lightyears away, could be habitable and capable of supporting human life, it was recently discovered.
But you might want to hold off on packing your bags and heading to your spacecraft for a visit, as the planet’s star might have blasted away its atmosphere.
The potentially habitable exoplanet, Gliese 12b, is about the size of Venus, and in what is known as the Goldilocks Zone of its host star, where the temperature allows liquid water to persist on the surface.
The surface temperature is an estimated 42ºC (107ºF) – warmer than the 15ºC (59ºF) average found here on Earth, but temperate enough that the planet’s water would neither freeze nor boil away.
“This is a really exciting discovery and will help our research into planets similar to Earth,” says Thomas Wilson from the University of Warwick.
Gliese 12b was first discovered by NASA’s Transiting Exoplanet Survey Satellite (TESS), after which Wilson and his colleagues undertook follow-up observations to confirm its existence and then measure characteristics, such as size, temperature and distance from Earth.
“The light we are seeing now is from 40 years ago – that’s how long it has taken to reach us here on Earth,” says Wilson.
“Planets like Gliese 12b are few and far between, so for us to be able to examine one this closely and learn about its atmosphere and temperature is very rare,” says Wilson.
Exoplanets around red dwarfs
There is no guarentee Gliese 12b is a habitable exoplanet, as it differs from Earth in several key ways.
It is much closer to its star, around 7% the Earth-Sun distance, and takes just 12.8 days to complete an orbit.
The host star is a red dwarf about the quarter the size of our Sun and with a much lower surface temperature.
This means despite Gliese 12b’s proximity, it receives only 1.6 times more energy than the Earth does from the Sun.
Red dwarfs have become a popular target for studying exoplanets, as their dimmer light means it is easier to pull out the subtle signals that allow astronomers to examine exoplanet atmospheres.
However, red dwarfs tend to be very magnetically active, meaning they produce frequent powerful flares that can strip away a planet’s atmosphere.
This star doesn’t show signs of being extreme behaviour, meaning the team are hopeful of being able to find an atmosphere around the planet.
“We know of only a handful of systems to date that are both close enough to us and meet other criteria needed for this kind of study, called transmission spectroscopy, using current facilities,” says Michael McElwain, from Goddard Space Flight Center who took part in the study. “To better understand the diversity of atmospheres around temperate planets similar to Earth, we need more examples like Gliese 12 b.”