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  Proxima b: A planet so Earth-like, and so close

Proxima b: A planet so Earth-like, and so close

AGENCIES
Published : Aug 26, 2016, 6:17 am IST
Updated : Aug 26, 2016, 6:17 am IST

The search for life outside our solar system just got a whole lot closer.

An artist’s impression of Proxima b
 An artist’s impression of Proxima b

The search for life outside our solar system just got a whole lot closer. Researchers have confirmed the existence of a rocky planet named Proxima b orbiting Proxima Centauri, the closest star to our sun, according to a new study.

The planet orbits Proxima Centauri every 11.2 Earth days and is five per cent the distance from its much-cooler red dwarf star as we are from our sun. This puts it in the not-too-hot, not-too-cold “Goldilocks Zone” where liquid water is possible, if the planet has an atmosphere. And it is a mere 4.22 light-years from Earth, or nearly 40 trillion kilometres.

Proxima b is not just within the habitable zone of its star, but also the closest possible home for life outside of our solar system, researchers said.

“We hit the jackpot here,” said Guillem Anglada-Escude , an astrophysicist at the Queen Mary University of London and lead author of the study published in journal Nature. He said the planet is “more or less what we have on Earth.”

“This is the best case we have of a potentially habitable planet and none will ever be found nearer than this,” said Paul Butler, co-author of the study.

“The key question of our initiative was whether there were potentially life-bearing planets orbiting these stars. We know now there is at least one planet with some characteristics similar to the Earth,” said Pete Worden, a former top Nasa manager, who was speaking at a European Southern Observatory webcast news conference to announce the find.

“Any talk about life on Proxima b is pure speculation. We won’t have a clue about life until we take the next step, which is direct imaging of the planet allowing us to study the atmosphere ... but that is realistically 20 years away,” Mr Butler said.

The international team of 31 scientists that announced the discovery did not actually see the planet. They deduced its existence indirectly, using telescopes to spot and precisely calculate the gravitational pull on the star by a possible orbiting body – a tried-and-true method of planet-hunting.

Astronomers got their first hint of a planet circling the sun’s small dim neighbour star in 2013. But they needed additional observations, using more precise instruments, to make a definitive call.

The shifts, which astronomers call “wobbles,” are caused by the gravitational tugging of a planet roughly 1.3 times the size of Earth on the parent star. Based on the timing of wobbles, scientists determined that the planet circles its host star in just 11 days, compared to Earth’s 365-day orbit around the sun.

That puts the planet far closer to its parent star than Earth orbits the sun. However, Proxima Centauri is so much smaller and dimmer than the sun that its planet’s orbit is suitably positioned for liquid water despite being just 4.4 million miles away.

“Chances are good that it’s a viable, Earth-like planet today,” said astronomer Pedro Amado, with the Instituto de Astrofísica de Andalucía in Granada, Spain.