Scientists have discovered an Earth-sized planet that could support life
(CNN) —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.
An exoplanet called Gliese 12b orbits a cool red dwarf star located in the constellation Pisces, according to two studies published Thursday in The Astrophysical Journal Letters and Monthly. Its size is about 27% of the size of our Sun and 60% of its temperature. Notices of the Royal Astronomical Society.
Because its star is much smaller than the Sun, Gliese 12b is still in the habitable zone (the ideal distance for a star where liquid water could exist), although it completes its orbit every 12.8 days.
Assuming the exoplanet has no atmosphere, scientists estimate its surface temperature to be about 107 degrees Fahrenheit (42 degrees Celsius).
“We have found the closest temperate Earth-sized transiting world to date,” said Masayuki Kuzuhara, an assistant professor on the project at the Tokyo Astrobiology Center and co-leader of one of the research teams with Akihiko Fukui on the project. This is stated in a message from an associate professor at the University of Tokyo.
Once Earth-sized temperate planets are identified, scientists will be able to analyze them to determine what elements are contained in their atmospheres and, crucially, whether water is present to support life.
“We have only found a few (exoplanets) that are good candidates for this. And this is the closest, and this is a pretty important finding,” Larissa Palthorpe, a doctoral student at the University of Edinburgh and University College London who led another study, told CNN on Friday.
Understanding Gliese 12b
To discover 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 each month, tracking changes in their brightness that could indicate the presence of exoplanets in orbit.
Astronomers have an easier time finding exoplanets orbiting red dwarfs because their relatively small size results in a larger dimming effect during each transit.
At this point, scientists aren’t sure what exactly the planet’s atmosphere, if any, is, or whether there is water there, although Palthorpe said they don’t expect to find water there.
“There can’t be water, and then we’ll know that this planet has already experienced a runaway greenhouse effect that will make it more like Venus,” he said. “There could be water there, which means it could be more like us… or there are signals that can be detected that could show that there is a runaway greenhouse effect going on, so there could be water loss.”
For the next step in analyzing the exoplanet’s atmosphere, scientists hope to use the James Webb Space Telescope and conduct spectroscopic analysis. The technique involves capturing starlight passing through an exoplanet’s atmosphere and observing which wavelengths are absorbed by certain molecules, revealing their presence in the atmosphere.
Palthorpe said scientists hope this work will not only shed light on the exoplanet itself, but also help us better understand our own planet.
“This planet in particular will teach us about what happened so that Earth remained habitable and Venus did not… It can tell us about the habitability paths that planets take as they evolve,” he said.
But while the exoplanet could potentially be suitable for human life and is relatively “close” to our solar system in astronomical terms, it is unlikely that anyone will visit it anytime soon.
“It’s unreachable, it’s 12 parsecs away,” Palthorpe said, adding that it would take about 225,000 years to reach Gliese 12b using the fastest spacecraft currently in existence.