Source: USA Today
Pandora, for the ancient Greeks, was a problem, popping open a pithos vase filled with all the ills of mankind. But thanks to the movie Avatar, Pandora offers a solution to one problem — what to call any hypothetically habitable moons orbiting one of the hundreds of Jupiter-sized jumbo planets discovered in the last decade. “Pandora” will do from now on to describe any such moons found in the future.
And James Cameron, Avatar‘s director, is hoping they find one. “We haven’t found a second Earth yet,” says Cameron, on the phone to promote the Earth Day release of his film on Blu-ray. “But there is still a chance for Alpha Centauri,” the double-star closest to our sun, and the setting for Pandora, the alien world in his environmentally-minded blockbuster science fantasy flick.
Since 1995, real-life astronomers have uncovered increasing numbers of worlds orbiting nearby stars, more than 400 so-called extra-solar planets so far. Increasingly, they are turning up Jupiter-lookalikes that orbit in the “habitable zone” of their stars, the region where water would neither boil nor freeze on the surface of a rocky moon orbiting a gas giant world.
In March, Europe’s CoRoT space telescope team in the journal Nature, reported “CoRot-9b,” a gas giant planet about 84% as massive as Jupiter, circling its star in a “temperate” orbit. Spain’s Hans Deeg of the Instituto de Astrofísica de Canarias in Tenerife, lead author of the study, said the team couldn’t rule out that a moon as large as Titan, Saturn’s haze-shrouded moon, orbits the planet.
In Avatar, Pandora is a tropical paradise moon orbiting a gas giant world in orbit around one of the two stars in the system, Alpha Centauri A and Alpha Centauri B. Those stars in turn circle each other once every 80 years or so, on an elongated orbit that carries them about as close to one another as Saturn comes to our sun. In the real world, no planets have turned up orbiting either star, Cameron acknowledges. But he and astronomers such as Greg Laughlin of the University of California, Santa Cruz, part of a team eyeballing the star system from the Cerro Tololo Inter-American Observatory in Chile, are still holding out hopes for Alpha Centauri.
Alpha Centauri A and B intrigue planet detectives because they are the closest sun-like stars to Earth at 4.4 light years away, about 26 trillion miles (a third red dwarf star, Proxima Centauri, about one-eighth the mass of the sun is thought to orbit both stars, and is a bit closer to us.) Even traveling at the same rate as the fastest rocket ever launched, NASA‘s New Horizons mission, a nine-year, 3-billion mile trip to Pluto, it would take at least 78,000 years to get there. But we can dream, can’t we? And it is closest.
Laughlin and colleagues received National Science Foundation funding for a five-year look for small Earth-like planets, detailed in a 2008 Astrophysical Journal paper, orbiting Alpha Centauri B. “We find that we can reliably detect a 1.8 (Earth-mass) planet in the habitable zone of (Alpha) Centauri B after only 3 years,” concludes the paper.
To read more: http://www.usatoday.com/tech/science/columnist/vergano/2010-04-25-extrasolar_N.htm