Astronomers¹ using ESO telescopes and other facilities have found clear evidence of a planet orbiting the closest star to Earth, Proxima Centauri. The long-sought world, designated Proxima b, orbits its cool red parent star every 11 days and has a temperature suitable for liquid water to exist on its surface. This rocky world is a little more massive than the Earth and is the closest exoplanet to us -- and it may also be the closest possible abode² for life outside the Solar System. A paper describing this milestone³ finding will be published in the journal Nature on 25 August 2016. Just over four light-years from the Solar System lies a red dwarf⁴ star that has been named Proxima Centauri as it is the closest star to Earth apart from the Sun. This cool star in the constellation⁵ of Centaurus is too faint to be seen with the unaided eye and lies near to the much brighter pair of stars known as Alpha Centauri AB.

 

During the first half of 2016 Proxima Centauri was regularly observed with the HARPS⁶ spectrograph on the ESO 3.6-metre telescope at La Silla in Chile and simultaneously⁷ monitored by other telescopes around the world. This was the Pale Red Dot campaign, in which a team of astronomers led by Guillem Anglada-Escudé, from Queen Mary University of London, was looking for the tiny back and forth⁸ wobble of the star that would be caused by the gravitational pull of a possible orbiting planet].

 

As this was a topic with very wide public interest, the progress of the campaign between mid-January and April 2016 was shared publicly as it happened on the Pale Red Dot website and via social media. The reports were accompanied by numerous outreach articles written by specialists around the world.

 

Guillem Anglada-Escudé explains the background to this unique search: "The first hints of a possible planet were spotted⁹ back in 2013, but the detection was not convincing. Since then we have worked hard to get further observations off the ground with help from ESO and others. The recent Pale Red Dot campaign has been about two years in the planning."

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