Scientists discovered a new Earth-sized exoplanet, hidden in data from the Kepler space telescope

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An artist’s impression of the newly discovered exoplanet - Image Credit: NASA / Ames Research Center / Daniel Rutter - HDR tune by Universal-Sci

Scientists discovered a new Earth-sized exoplanet, hidden in data from the Kepler space telescope. The scientists shared their findings in a paper in the well-known science journal: Astrophysical Journal Letters. The planet (Kepler-1649c) orbits its host star within the so-called habitable zone, also known as the goldilocks zone, a zone where liquid surface water can exist.

Kepler-1649c is only slightly larger than Earth, 6% to be exact, and is located at a distance of approximately 300 light-years. The star system, of which the exoplanet is a part, hosts one additional, Venus-like planet that has been discovered a few years ago. The host star is roughly a quarter the size of our Sun.

Old data, new discovery

The Kepler space telescope, whose data has led to this discovery, was retired two years ago. Kepler-1649c has only now been discovered because researchers recently reviewed old data. And where previous searchers with an algorithm misidentified it, it has now been confirmed to be an exoplanet. Perhaps even more remarkable, Kepler-1649c is the most analogous exoplanet to Earth out of all the exoplanets found by the Kepler telescope.

Kepler-1649c size comparison - Image Credit: NASA/Ames Research Center/ Daniel Rutter - HDR tune by Universal-Sci

Jeff Coughlin, SETI Institute scientist and co-author of the study, mentioned that there are a huge number of signals that aren't generated by exoplanets. Examples are signals created by variable stars and spurious noise from Kepler's electronics. It took the research team years of studying these signals in-depth to gain the human expertise to distinguish these signals reliably, and then years more to write the computer algorithms to do it automatically.

According to Andrew Vanderburg, first author of the before mentioned paper, out of all the mislabeled exoplanets that have been recovered, this one is particularly exciting, not only because it is located within the habitable zone and the approximate size of Earth, but because of how it might interact with this neighboring planet. Like before mentioned, the star system has another rocky planet of approximately the same size, but it orbits the star at about half the distance, somewhat akin to how Venus orbits our Sun in comparison to Earth.

The surface temperature of the newly discovered planet might be comparable to that of Earth as it receives about 75% of the amount of light from its host star. It orbits its small red dwarf star so tightly that a year on takes only 19.5 Earth days. One caveat for the existence of potential life, though, is the fact that it orbits a red dwarf star. Red dwarf stars are known for their volatile nature. Stellar flares are quite common; however, as of yet, none have been witnessed.

An artist’s impression of the planet’s surface - Credit: NASA/Ames Research Center/Daniel Rutter - HDR tune by Universal-Sci

There is still a lot that is undiscovered about Kepler-1649c, including its atmosphere, which could influence the planet's surface temperature. However, based on what is known, Kepler-1649c is fascinating for scientists searching for worlds with a possible environment that is fit for life.

There is some evidence for a possible third planet in the system. The science team looked for proof of such a third mystery planet but ended up fruitless. That doesn't mean that it doesn't exist, though, as the planet could be at an orbital tilt that makes it impossible to locate or simply because it is too small to observe.

Thomas Zurbuchen, associate administrator of NASA's Science Mission Directorate in Washington, noted that the data gathered by missions like Kepler and TESS will continue to yield amazing discoveries like this as the ability to look for promising planets is being refined continuously.

Sources and further reading: NASA JPL press release / SETI institute press release / Kepler space telescope