NASA has discovered an Earth-like planet 40 light-years away that could be a promising candidate for harboring human life.
The exoplanet, called Gliese 12 b, is slightly smaller than our planet and has an estimated surface temperature of 107 degrees Fahrenheit – assuming it has no atmosphere.
Gliese 12 b is just inside the habitable zone – the distance from a star at which liquid water could exist on the surfaces of orbiting planets.
Astronomers now plan to analyze Gliese 12 b to determine whether it has an Earth-like atmosphere. This could reveal whether the exoplanet can maintain the right temperature for water to form on its surface – an essential component for supporting life.
Gliese 12 b is being billed as the “closest transiting temperate Earth-sized world to date” and is a candidate for future exploration by NASA’s $9.5 billion James Webb Space Telescope.
An international team of astronomers discovered Gliese 12 b, an exoplanet located 40 light-years from Earth and with a surface temperature of 107 degrees Fahrenheit. Pictured: Image of the location of Gliese 12 b in 1998 (left) and 1949 (right)
An international team of astronomers used NASA’s TESS (Transiting Exoplanet Survey Satellite) to determine the location of Gliese 12 b.
These discoveries are usually made using the ‘transit method’: when the planet passes in front of its star, causing its brightness to decrease.
During the exoplanet’s transit, the star’s light passes through the atmosphere and absorbs some of the wavelengths, releasing gas molecules that telescopes such as the James Webb can detect.
The team found that Gliese 12 b has a much closer orbit than Earth, meaning it passes its cool red dwarf star, called Gliese 12, more often, completing an orbit every 12.8 days.
“Gliese 12 b is one of the best targets to study whether Earth-sized planets orbiting cool stars can maintain their atmospheres, a crucial step in advancing our understanding of the habitability of planets in our Milky Way,” says Shishir Dholakia, a PhD candidate at the Center for Astrophysics at the University of Southern Queensland in Australia.
The exoplanet’s distance from its dwarf star is only seven percent of the distance between Earth and the Sun, giving it 1.6 times more energy.
However, Gliese 12 b’s habitable conditions depend on whether it has the same type of atmosphere as Earth, making its temperature closer to our planet’s average of 59 degrees Fahrenheit.
Astronomers have discovered about 5,000 exoplanets, but estimate there are probably more than a trillion in the Milky Way alone. Pictured: location of Gliese 12 b
“Atmospheres trap heat and – depending on their type – can significantly change the actual surface temperature,” Dholakia explains.
‘We quote the planet’s ‘equilibrium temperature’, the temperature the planet would be if there were no atmosphere.
The team compared Gliese 12 b to Venus and reported that it is about the same size and receives slightly less energy from its star: about 85 percent.
But because Venus has no atmosphere to block the sun’s harmful rays, it developed a greenhouse effect, reaching temperatures of 752 degrees Fahrenheit.
“Earth is habitable, but Venus is not due to the complete loss of water,” says Larissa Palethorpe, a doctoral student at the University of Edinburgh and University College London.
“Because Gliese 12 b is between Earth and Venus in temperature, its atmosphere can teach us a lot about the habitability pathways that planets follow as they evolve,” she added.
A key factor in understanding whether the exoplanet could be habitable is looking at the level of storms emitted by its star.
Red dwarf stars are usually magnetically active, so they regularly project X-ray flares that can destroy the atmosphere.
The teams are hopeful that this is not the case, as the Gliese 12 star shows no signs of extreme storms or behavior.
Astronomers have already discovered roughly 5,000 of these planets, but estimate that there are probably more than a trillion exoplanets in the Milky Way alone; so far, only a handful are believed to have the environment necessary to sustain life.
“We know of only a handful of temperate planets that are similar to Earth and both of which are close enough to us and meet other criteria needed for this kind of research,” said Michael McElwain, an astrophysicist at NASA’s Goddard Space Flight Center and co-author. of the Gliese 12 b study.
“To better understand the diversity of the atmospheres and the evolutionary outcomes for these planets, we need more examples like Gliese 12 b,” he added.