Astronomers Just Discovered an "Earth-Like" Planet


The best candidate for an 'Earth twin' is called EPIC 201497682.03.

Astronomers have just found 18 Earth-sized exoplanets, a huge feat in itself, but one of them looks remarkably similar to our own planet. Could a new technique in the hunt for Earth 2.0 help astronomers find 100 new 'Earth twins?'

Image result for EPIC 201497682.03

If an exoplanet travels in front of its star as seen from Earth, the planet darkens the star. How often that happens tells astronomers about the length of a year on the planet. However, the new algorithm by Heller, Rodenbeck and Hippke does not look for abrupt brightness drops like earlier standard algorithms, but for gradual darkening. This makes the new transit search algorithm significantly more sensitive to very small planets the size of the Earth.

Small planets are harder to track down than big ones. Exoplanet-hunters find their targets by detecting a drop in brightness as a planet travels (transits) in front of its host star. However, while large planets cause sudden drops in brightness that is easy to detect, small planets cause such a tiny change in brightness that it's hard to separate it from the natural brightness fluctuations of the star.

Image result for EPIC 201497682.03

“Standard search algorithms attempt to identify sudden drops in brightness," said Heller. “In reality, however, a stellar disk appears slightly darker at the edge than in the center. When a planet moves in front of a star, it therefore initially blocks less starlight than at the mid-time of the transit. The maximum dimming of the star occurs in the center of the transit just before the star becomes gradually brighter again. Our new algorithm helps to draw a more realistic picture of the exoplanet population in space," summarises Michael Hippke of Sonneberg Observatory

The researchers used data from NASA’s Kepler Space Telescope as a test bed for their new algorithm. In its first mission phase from 2009 to 2013, Kepler recorded the light curves of more than 100,000 stars, resulting in the discovery of over 2,300 planets. After a technical defect, the telescope had to be used in an alternative observing mode, called the K2 mission, but it still managed to monitor more than 100,000 more stars by the end of the mission in 2018. The researchers decided to re-analyze all 517 stars from K2 that were already known to host at least one transiting planet.

Can the new algorithm be used to find another Earth 2.0?

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