First ‘habitable’ exoplanet confirmed

Gliese 581d is the outlying planet in the Gliese 581 system, and orbits its parent star every 66.8 days. It may be covered by a large and deep ocean and is the first serious 'waterworld' candidate discovered beyond our Solar System.

A rocky world orbiting a nearby star was confirmed as the first planet outside our Solar System to meet key requirements for sustaining life.

Modelling of planet Gliese 581d shows it has the potential to be warm and wet enough to nurture Earth-like life, scientists have said. It orbits a red dwarf star called Gliese 581, located around 20 light years from Earth, which makes it one of our closest neighbours.Gliese 581d orbits on the outer fringes of the star’s ‘Goldilocks zone’, where it is not so hot that water boils away, nor so cold that water is perpetually frozen. Instead, the temperature is just right for water to exist in liquid form.

“With a dense carbon dioxide atmosphere – a likely scenario on such a large planet – the climate of Gliese 581d is not only stable against collapse but warm enough to have oceans, clouds and rainfall,” France’s National Centre for Scientific Research (CNRS) said.

More than 500 planets orbiting other stars have been recorded since 1995, detected mostly by a tiny wobble in stellar light. Exoplanets are named after their star and listed alphabetically, in order of discovery.

Until now, the big interest in Gliese 581’s roster of planets focussed on Gliese 581g. It leapt into the headlines last year as ‘Zarmina’s World’, after its observers announced it had roughly the same mass as Earth’s and was also close to the Goldilocks zone.

via First ‘habitable’ exoplanet confirmed

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