NASA's Kepler spacecraft may have retired in November 2018, but its discoveries keep rolling in as scientists found an Earth-size world that may be capable of supporting life as we know it.
According to the new study, the Kepler-1649c is an exoplanet that circles a red dwarf star somewhere in space that is 300 light-years away from Earth. It completes one orbit every 19.5 days making Kepler 1649-c in its host star's "habitable zone." It is just the right distance for a planet to have liquid water on its surface.
As Thomas Zurbuchen, an associate administrator of NASA's Science Mission Directorate said in a statement, this intriguing alien planet gives us hope that an Earth-like planet is waiting to be found among the stars.
The "transit method"
Using the "transit method" the Kepler spacecraft was able to hunt for planets. The method involves monitoring the stars for tiny brightness dips from planets that are crossing their faces from the spacecraft's viewpoint.
Kepler was able to do it through two phases. The first one was on its main mission that lasted until 2013. The second time was during the K2 which is an extended mission that ended 17 months ago when Kepler ran out of fuel.
Both campaigns of the spacecraft was successful after Kepler spotted about two-thirds of the confirmed exoplanets that astronomers have discovered until today. Kepler's findings suggest that a lot of potentially life-supporting planets in the Milky way host rocky worlds that are in the habitable zone. That is about 20-25% of the 2 billion stars or more.
Astronomers have a lot of work to do with Kepler's huge data set. It involves double-checking and trying to dig up bona fide planets that were mislabeled as false positives by previous screening software. Many of these false positives are in the Kepler data because other things can cause stellar brightness dips that are orbiting the planets and therefore it is difficult to identify which one is real.
Even Kepler-1649c was once wrongly thrown as a false positive that researchers only discovered after forming the Kepler False Positive Working Group. They published their findings on April 15 on The Astrophysical Journal Letters.
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Can humans survive there?
Kepler-1649c has a neighboring planet that also orbits the red dwarf at about half the distance called the Kepler-1649b. This too is probably too hot and may not able to support life.
It is still hard to measure Kepler-1649c's true habitability prospects as astronomers do not know anything about the planet's atmosphere yet. The composition and thickness of a world's atmosphere depends on its temperature and the surface water's ability to maintain in a liquid phase.
Moreover, planets in their habitable zones may get their atmospheres stripped relatively quickly because red dwarf stars unleash powerful flares especially in their younger years. But red dwarves are common in the Milky Way's stellar population so it is easy to imagine that there could be a lot of worlds outside our solar system that could support life.
Study lead author and University of Texas' researcher at Austin said that more data are needed to see more signs that point to the notion that potentially habitable Earth-size exoplanets are common around red dwarf stars.
"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," Vanderburg said.
