HABITABLE ALIEN WORLD discovered 20 light-years away!
War inevitable if advanced life present, thanks to Bebo
Stargazing boffins say they have discovered evidence of a potentially habitable world orbiting a star just 20 light-years from Earth. They add that the circumstances of the discovery suggest that the galaxy may be "teeming with potentially habitable planets".
What's this barbaric rubbish on the interstellar band? It's coming from that G-type over there, you say, Commander? Despatch a volley of krenon torpedoes immediately
The star in question is Gliese 581 in the constellation Libra, whose planets have been in the scientific news for some years now. In particular, boffins have tended to focus on the planet Gliese 581d, which has around seven times the mass of Earth. It lies at such a distance from its dim, red M-class sun as to make it pretty cold, but some scientists say that if conditions on the surface are right liquid water could perhaps exist there.
Now, however, a team of boffins from the Lick-Carnegie Exoplanet Survey have brought a new method into play: that of measuring tiny movements of the star in response to gravitational pulls upon it by its orbiting planets. Compiling 11 years' worth of radial velocity measurements of Gliese 581, the scientists say they have found two new planets, Gliese 581 f and g. It is Gliese 581g, massing about three times what Earth does, that is of interest:
The estimated equilibrium temperature of GJ 581g is 228 K, placing it squarely in the middle of the habitable zone of the star and offering a very compelling case for a potentially habitable planet around a very nearby star.
The given temperature of 228 Kelvin equates to 45 degrees below zero on the everyday Celsius scale, but the Carnegie scientists believe that surface temperatures would average between -31°C and -12°C. As it is very close to its parent star, the planet is liable to be tidally locked - with one face constantly turned to its primary, as the Moon is to Earth here in our solar system. This would lead to blazing heat on the bright side and freezing chill on the dark, and bands of intermediate temperature in between.
Though much more massive than Earth, Gliese 581g is also assessed as being perhaps half again as big. Thus its surface gravity would be anywhere from 1.1 to 1.7 g - good for holding an atmosphere, and quite feasible for humans to walk about in.
The Carnegie team says that the mere fact of Gliese 581g being found almost as soon as the new radial-velocity boffinry tool was put into use suggests that "eta_Earth", the fraction of stars which have potentially-habitable planets, is likely to be large - "on the order of a few tens of percent". They add:
If the local stellar neighborhood is a representative sample of the galaxy as a whole, our Milky Way could be teeming with potentially habitable planets.
Potentially habitable but as yet uninhabited worlds would be great, as soon as humanity can master the various technical issues involved in star travel (just getting past low orbit seems to be beyond us at the moment). The human race could spread out across many planetary homes, and so finally achieve a decent chance of long-term survival (if we don't manage this, we're certain to be wiped out at some point in an unfortunate asteroid or comet strike, global war, climate change or something).
Of course, habitable worlds might also be inhabited by life more complex than the microbial forms which have been all there was on Earth for almost all the time it has been a living planet. In the case of Gliese 581, the presence of advanced intelligent life would be a disaster for humanity.
If there are advanced aliens at Gliese 581, we have already offended them seriously
Why Gliese 581 in particular, you may ask, should you not be a regular reader of Reg exoplanet coverage.
The answer to this is simple. During 2008, in an ultimately futile* attempt to add some buzz and value to their company, the bosses of Bebo took it into their heads to beam a powerful radio message  at the Gliese 581 system. This in itself might not have been such a bad a idea, but sadly they chose to use as their message a selection of text and imagery submitted by devotees of the web-2.0 teenybopper portal.
As one might expect the resulting material focused on matters of interest only to mental cripples. There were many pictures of cats, boy crooners and other prominent figures in the Bebo userbase lifestyle. There were also many personal messages, a few of which we reproduce here:
Our bodies are made of bones ... We have senses. Smell, Taste, Sight and Touch. Without any of these things, we wouldn't live.
I love Television. We watch animated cartoons and real-life drama on it. I could sit and watch Television all day.
Hi im nicole. my ambitions for when i am older is to perform, i love anything to do with drama and someday i would love to appear on the west end stage, in a hit show.i also wouldnt mind doing a few television programs whether it is as a extra or a main part i dont mind i would love to appear on doctor who as i love it. anyway laters.Nicole x
Bebo execs hired unscrupulous Russian astronomer Alexander Zaitsev to beam the frightful guff-blast at Gliese 581 from a powerful Ukrainian radar telescope, and it will duly arrive at that star system in March 2029. In the event of sentient alien life being present, we can presumably expect a well-deserved planetsmasher missile strike by return of post at some point after 2049 (provided the aliens haven't mastered faster-than-light travel).
Let's all hope that any denizens of the possible, habitable Sunrise Belt of Gliese 581g - or perhaps of 581d, should it in fact be habitable - have failed to evolve beyond the level of pondlife or primitive gibbering tree-dwellers, and as such will not be offended by the Bebo drivel-blast solecism.
And meanwhile, since if the Carnegie boffins are correct the sky is bursting with habitable worlds, let's be a bit more careful about what we beam out into the void. And let's get cracking on those starships, already, before some galactic equivalent of the Germans chuck their beach-towels on all the best planets.
Those interested can read the Carnegie team's research in advance of publication here . ®
*Bebo is circling the drain. It was to be shut down, but eventually  AOL managed to flog it off at a tiny fraction of its original valuation to investors who specialise in turning around small dysfunctional companies.