One Of The Most Earth-Like Worlds We've Found May Not Actually Exist

Artist's impression of Kepler-452b. NASA/JPL-Caltech/T. Pyle

Back in 2015, astronomers announced the groundbreaking discovery of a world not too unlike our own – Kepler-452b. But a new study has cast doubt on whether the planet really exists.

Kepler-452b, located around a star 1,400 light-years from Earth, was immediately exciting for being Earth-sized (1.6 times our planet) and orbiting a Sun-like star. That star is 1.5 billion years older than ours, leading some to suggest the planet was an older cousin of Earth.

As picked up by Scientific American, however, there is a statistical chance that the planet does not exist. Looking at data from the primary mission of Kepler, a study accepted for publication in the Astrophysical Journal and available on arXiv found a number of planets in Kepler’s data that aren’t guaranteed to be real, including this one.

“We show statistical validation is insufficient to confirm Kepler-452b at the 99 percent level, and that Kepler-452b should no longer be considered a confirmed planet,” the researchers, led by the SETI Institute in California, note in their paper.

The team said there was a 16 to 92 percent chance that the planet is real, depending on how optimistic they’re being. They came to this conclusion by averaging out errors from the mission and working out which signals could be either false alarms or erroneous noise from the telescope’s instrument.

Looking at more than 100,000 stars found by Kepler, which is due to end in several months, the team found that planets similar in size to Earth with orbits larger than 200 days were the hardest to confirm as real, as their transits were both small and infrequent.

This doesn’t mean that Kepler-452b isn’t a planet. Speaking to Scientific American, Natalie Batalha, a co-author on the Kepler-452b discovery paper, said this problem was already known about, and the authors don’t consider planets on a case-by-case basis, which is what made Kepler-452b promising.

NASA’s Exoplanet Science Institute, which catalogs worlds beyond our Solar System, said Kepler-452b would retain its status for now, until “a more definitive refutation” is published. Confirming this one way or another, however, might be tricky.

The planet is due to make its next transit on April 18. The only telescope that could feasibly see this transit, if the planet really exists, is Hubble. But there’s not enough time to get a proposal to use the telescope to look at the planet. So astronomers may have to wait for the planet’s next transit, May 8, 2019, to get to the bottom of it.

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