Two teams of scientists have discovered a theoretically habitable planet, smaller than Earth but larger than Venus, orbiting a small star about 40 light-years away.
O exoplanetcalled Gliese 12borbits a cool red dwarf star located in the constellation Pisces and is about 27% the size of our Sun and 60% its temperature, according to two studies published on Thursday (23) in the magazines The Astrophysical Journal Letters and Monthly Notices of the Royal Astronomical Society.
An exoplanet is a planet that is outside the Solar System.
Because its star is much smaller than the Sun, Gliese 12b is still within the habitable zone — the ideal distance from a star where the liquid water can exist — even though it completes its orbit every 12.8 days.
Working under the assumption that the exoplanet has no atmosphere, scientists calculated that its surface temperature is about 107 degrees Fahrenheit (42 degrees Celsius).
“We have found the closest transiting, Earth-sized, temperate world located to date,” said Masayuki Kuzuhara, assistant professor at the Center for Astrobiology in Tokyo and co-leader of one of the research teams with Akihiko Fukui, assistant professor at the University of Tokyo, in a statement.
Once temperate planets similar in size to Earth have been identified, scientists can then analyze them to determine what elements are contained in their atmospheres and, crucially, whether there is water present to support life.
“There are only a handful (of exoplanets) that we have found that are good candidates for this. And this is the closest to us, so it’s a pretty important discovery,” Larissa Palethorpe, a PhD candidate at the University of Edinburgh and University College London who co-led the other study, told CNN on Friday (24).
Understanding Gliese 12b
To identify Gliese 12b, scientists used publicly available data collected by NASA’s Transiting Exoplanet Survey Satellite (TESS) — a telescope that observes tens of thousands of stars every month, tracking their changes in brightness, which could be evidence of exoplanets in orbit.
It is easier for astronomers to find exoplanets orbiting red dwarf stars, as their relatively small size results in a greater dimming effect during each transit.
Right now, scientists aren’t sure what the makeup of this planet’s atmosphere is, if it has one, and whether water is present, although Palethorpe said they don’t expect to find water there.
“There may not be water, and then we know that a runaway greenhouse effect has already happened on this planet and it is more like Venus,” she said. “There could be water, in which case it’s more like us… or there are signatures that might be detectable that would show that the runaway greenhouse effect is in progress, so it could be losing water.”
For the next phase of analyzing the exoplanet’s atmosphere, scientists hope to use the James Webb Space Telescope to perform spectroscopic analysis. This method involves capturing starlight as it passes through an exoplanet’s atmosphere and seeing which wavelengths are absorbed by certain molecules, revealing their presence in the atmosphere.
In addition to shedding light on the exoplanet itself, Palethorpe said scientists hope this work can help us better understand our own planet.
“What this planet will teach us, in particular, is what happened for Earth to remain habitable but Venus did not… This can tell us the habitability paths that planets follow as they develop,” she said.
But although the exoplanet could potentially be habitable for humans and is relatively “close” to our Solar System in astronomical terms, it is unlikely that anyone will visit it anytime soon.
“It’s not reachable, it’s 12 parsecs away,” said Palethorpe, adding that it would take about 225,000 years to reach Gliese 12b with the fastest spacecraft currently in existence.
Discover the oval-shaped exoplanet about 1,200 light years from Earth
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