@CalamityJane,
To Infinity & Beyond! Terrestrial-mass Exoplanet
Planet with British weather found 20 light years away
Cold, rainy, inhabitants likely to be hostile
Posted in Space, 17th May 2011 15:11 GMT
A group of boffins claims to have spied the "first discovered terrestrial-mass exoplanet in the habitable zone", the BBC reports.
The planet in question is orbiting the much-studied star Gliese 581, some 20 light-years away in the constellation Libra. Of the possible worlds orbiting the red M-class sun, Gliese 581d had already been proposed as a repository of water, although previous studies suggested its distance from the solar system's centre means it would be too cold for liquid H2O.
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Gliese 581d then took centre stage as perhaps the first known habitable alien world, but the very existence of that planet has been called into serious doubt.
The astronomers from the Institut Pierre Simon Laplace in Paris have now re-evaluated Gliese 581d, declaring it first Blighty-like exoplanet – cold, rainy and just about capable of supporting life. Their simulations point to a dense, CO2 atmosphere which would provide "a signicant greenhouse effect" to raise the mean global temperature above 0°C.
There are a couple of minor impediments to human colonisation of Gliese 581d, however. The atmosphere is, in common with our own Middlesbrough, toxic. The planet is also probably tidally locked to its sun, meaning one side in permanent darkness, and the other with light perpetually struggling to penetrate the fug.
http://www.theregister.co.uk/2011/05/17/blighty_exoplanet/
Life is most likely to form within the circumstellar habitable zone (CHZ) within a solar system, and the galactic habitable zone (GHZ) of the larger galaxy (though research on the latter point remains in its infancy). The HZ may also be referred to as the "life zone", "Comfort Zone", "Green Belt" or "Goldilocks Zone".
"This porridge is too hot," Goldilocks exclaimed.
So she tasted the porridge from the second bowl.
"This porridge is too cold."
So she tasted the last bowl of porridge.
"Ahhh, this porridge is just right!" she said happily.
And she ate it all up.
A "Goldilocks planet" is a planet that falls within a star's habitable zone, and the name is often specifically used for planets close to the size of Earth. The name comes from the story of Goldilocks and the Three Bears, in which a little girl chooses from sets of three items, ignoring the ones that are too extreme (large or small, hot or cold, etc.), and settling on the one in the middle, which is "just right". Likewise, a planet following this Goldilocks Principle is one that is neither too close nor too far from a star to rule out liquid water on its surface and thus life (as humans understand it) on the planet. However, planets within a habitable zone that are unlikely to host life (e.g., gas giants) may also be called Goldilocks planets. The best example of a Goldilocks planet is the Earth itself.
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.
Libra (♎) is the seventh astrological sign in the Zodiac, originating from the constellation of Libra. In astrology, Libra is considered a "masculine", positive (extrovert) sign. It is also considered an air sign and is one of four cardinal sins errrrrrr signs. Libra is ruled by the planet Venus (which also rules Taurus).
Could be a load of bull... but who knows!
Onwards and upwards - we do endeavour!
I spy, with my little eye, Goodness Gracious, Great Balls of Fire !