A team of transatlantic scientists taking a second look at data observations from NASA’s Kepler space telescope, which the agency retired in 2018, have discovered an earth-size exoplanet orbiting in its star’s habitable zone, the space agency announced in a press release on April 15.
The planet, called Kepler-1649c, is located 300 light-years from Earth and is most similar to it in size and estimated temperature, being just 1.06 times larger than our planet, NASA said. The amount of starlight it receives from its host star is 75 percent of the amount of light Earth receives from our sun, suggesting the exoplanet’s temperature may be similar to Earth’s too.
Kepler-1649c is also located within the habitable zone of its star, existing at just the right distance where liquid water can exist on the surface, suggesting that it could potentially support life as we know it.
Unlike Earth though, it orbits a red dwarf star. Such stars make up the largest population of stars in the galaxy and are much smaller and cooler than our Sun. Though none have been observed in this system, this type of star is known for stellar flare-ups that may make a planet’s environment challenging for any potential life.
While much is still unknown about the new-found exoplanet, including its atmosphere, which could affect its temperature, and correct size, NASA said the discovery is intriguing for scientists searching for worlds with potentially habitable conditions.
“This intriguing, distant world gives us even greater hope that a second Earth lies among the stars, waiting to be found,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate in Washington. “The data gathered by missions like Kepler and our Transiting Exoplanet Survey Satellite [TESS] will continue to yield amazing discoveries as the science community refines its abilities to look for promising planets year after year.”
The exoplanet joins other’s that are estimated to be closer to Earth in size, like TRAPPIST-1f, while TRAPPIST-1D and TOI 700d are considered to be closer to Earth in temperature. However, Kepler-1649c is by far the most intriguing exoplanet yet as it may be similar in both size and temperature to Earth and lies in the habitable zone of its system.
According to Nasa, Kepler-1649c was overlooked because a computer algorithm called Robovetter, which helps to sort through massive amounts of data produced by the Kepler spacecraft, classified it as false positive. Astronomers know computers make mistakes, so researchers in the Kepler False Positive Working Group, analyze all the false positives to ensure they are genuine errors and not exoplanets, took another look. As it turns out, Robovetter had mislabeled Kepler-1649c, and thus, it was identified as a planet.
“Out of all the mislabeled planets we’ve recovered, this one’s particularly exciting—not just because it’s in the habitable zone and Earth-size, but because of how it might interact with this neighboring planet,” said Andrew Vanderburg, a researcher at the University of Texas at Austin and first author of the study. “If we hadn’t looked over the algorithm’s work by hand, we would have missed it.”
Researchers believe there may also be a third planet in the system but have so far been unable to spot it. They noted that this might be because it’s too small to see or is at an orbital tilt that makes it impossible to find using Kepler’s transit method.
“The more data we get, the more signs we see pointing to the notion that potentially habitable and Earth-size exoplanets are common around these kinds of stars,” said Vanderburg. “With red dwarfs almost everywhere around our galaxy, and these small, potentially habitable and rocky planets around them, the chance one of them isn’t too different than our Earth looks a bit brighter.”