30 September 2010
Even more fascinating Exoplanet news
Back in 2007 I put up a post about the discovery of an exoplanet Gliese 581c. At the time it was one of three planets discovered around the red dwarf star Gliese 581c which is just 20 light years from earth ( Just down the road in astronomical terms but for the foreseeable future it may as well be on the other side of the universe in terms of getting up close and personal).
Gliese 581c is close to the star’s so called Goldilocks zone (aka the Habitable Zone or HZ - the band around a star where water can exist in liquid form and thus amenable to life…. or at least life that may be remotely earth-like). At the time it was the smallest know extra solar planet was considered a possible location of extrasolar life.
Gliese 581 seems to be a goldmine for exoplanets: In 2009, 581d, a “super-earth” was found to be in the HZ; 581e, although beyond the HZ is at 1.9 times the mass of the earth the smallest exoplanet so far.
And there’s more!
According to today’s Guardian there is yet another planet , Gliese 581g , which is potentially habitable (being in the HZ) and of a similar size to Earth.
Gliese 581g, has a mass of three to four times that of Earth and takes 37 days to orbit the star. Astronomers believe it is a rocky planet with enough gravity to retain an atmosphere.
One side of the planet is always facing the star, much as one side of the moon constantly faces Earth. This means that the far side of the planet is constantly in darkness. The most habitable region of the planet would be the line between the light and dark regions.
The average temperature on the planet is estimated to be between -31 to -12C, but the ground temperature would vary from blazing hot on the bright side and freezing on the dark side.
"Our findings offer a very compelling case for a potentially habitable planet," said Steven Vogt, an astronomer at the University of California, Santa Cruz. "The fact that we were able to detect this planet so quickly and so nearby tells us that planets like this must be really common."
"The number of systems with potentially habitable planets is probably on the order of 10 or 20 percent, and when you multiply that by the hundreds of billions of stars in the Milky Way, that's a large number. There could be tens of billions of these systems in our galaxy,"
This is utterly fascinating stuff. I can imagine that such discoveries will be come more and more commonplace.. I can only imagine what newer and more advanced telescopes will reveal.
Shame that we will never see them in the flesh though