سیارهای در فاصله بیست سال نوری منظومه شمسی کشف شده که دانشمندان آنرا مناسب برای زندگی تشخیص داده اند. / این سیاره شرایطی شبیه زمین را برای زندگی دارد، از جمله بارش باران و حتی اقیانوس آب/ دما آنقدر زیاد نیست که آب

 بخار شود و آنقدر کم هم نیست که یخ بزند./ البته اتمسفر آن پر است از دی اکسید کربن و قدرت جاذبه نیز دو برابر زمین است./ با حجمی 5.6 برابر زمین ، آنرا در دسته ابر سیاره جا داده اند./ تحقیقات جدید ، سیاره را قابل زندگی ارزیابی می کند

A planet 20 lightyears away is the first outside our solar system to be declared ‘habitable’ byscientists.

The rocky‘exoplanet’ Gliese 581d meets key requirements for sustaining Earth-like life,including rainfall and possibly even watery oceans.

The planet orbits ared-dwarf star similarly called Gliese 581, on its outer fringes called the‘Goldilocks zone’, where the temperature is not so hot that water boils away, nor so cold that water isperpetually frozen.

But even though itmay be technically habitable, the Gliese 581d would not make a comfortabledwelling for humans.

Gravity is twicewhat is on Earth, doubling the weight of anyone standing on the surface, andthe atmosphere is dense with carbon dioxide.

With a mass of atleast 5.6 times that of Earth, Gliese 581d is classified as a ‘super-Earth’.

The discovery caughtscientists by surprise because the planet was previously ruled out as ahabitable country.

But a new computermodel with the capacity to simulate extraterrestrial climates has confirmedthat Gliese 581d really could harbour life, showing the prior assumption to bewrong.

"This discovery isimportant because it’s the first time climate modellers have proved that theplanet is potentially habitable, and all observers agree that the exoplanetexists,” said Dr Robin Wordsworth, a member of the French team from theInstitut Pierre Simon Laplace in Paris.

"If you look at thehistory of the search for habitable planets, there’s been at least twoinstances so far when scientists have announced that a habitable world has beendiscovered, only to have the claim contradicted later, either by climateexperts or by other observers.”

On average, thelight that Gliese 581d receives from its star has about 30 per cent of theintensity of sunlight on Earth.

While thattemperature seems too cold to support liquid water, the atmosphere’s highproduction of greenhouse gases significantly heats the planet.

It may also be"tidally locked", meaning that one side of it always faces the sun,which would give it permanent dayside and nightside.

More than 500planets orbiting other stars have been recorded since 1995, detected mostly bya tiny wobble in stellar light.

Exoplanets are namedafter their star and listed alphabetically, in order of discovery.

Until now, the biginterest in Gliese 581’s roster of planets focused on Gliese 581g.

It swept theheadlines last year as ‘Zarmina’s World’, after its observers announced it hadroughly the same mass as Earth’s and was also close to the ‘Goldilocks zone’.

But that discoveryhas since been discounted by many, with some experts suspecting the Gliese 581gmay not even exist.