Scientists pleasantly surprised by number of Earth-size, distant planets

The planet Kepler-10b orbits a star similar to our own Sun in its temperature, 
mass and size.

February 19th, 2011
06:02 PM ET


Where might extraterrestrials live? The first step is figuring out what other 
planets out there have conditions like our own.

Scientists using NASA's Kepler space telescope are working hard to find 
candidates for inhabitable planets. So far, it seems that for approximately 
every two stars in the galaxy, there is one possible planet, NASA's William 
Borucki said Saturday at the American Association for the Advancement of 
Science annual meeting in Washington.

Researchers have found some 1,200 candidate-planets and, of them, about 54 are 
earth-size candidate planets in habitable zones - in other words, perhaps at a 
distance from their stars that may be suitable for life. Earlier this month 
officials at NASA announced the discovery of five probable planets about the 
size of Earth, as well as six larger than our planet that are orbiting a single 
star. But bear in mind that Venus is also considered an "Earth-sized planet," 
and clearly no lifeforms live there (as far as we know).

Scientists on the Kepler mission revealed Saturday that you're probably going 
to have to wait until at least 2012 to find out anything substantial about the 
habitability of what appear to be Earth-sized planets. That's because 
scientists need to be able to see three transits of a planet around a star in 
three years before they'd be willing to say too much about them, and the 
project has only been going since 2009 (after all, our planet goes around the 
sun three times in three years).

And even then, Kepler wasn't designed to look at individual planets. But it 
might identify some that the James Webb Space Telescope, which will launch in 
2014, can probe in further detail, looking at atmospheres and such. And note 
that the probability of having found our own particular planet using Kepler 
technology is only 12%.

And we won't be traveling to meet our potential new neighbors anytime soon. The 
stars about the size our sun that Kepler has been looking at are about 1,000 to 
3,000 light years away, where one light year is about 6 trillion miles.

But there have been some fascinating surprises from the Kepler mission. One of 
them is that there appear to be a remarkable number of planets about the size 
of Neptune, which has a diameter four times that of Earth, said Sara Seager, 
physicist at Massachusetts Institute of Technology.

The planet Kepler-10b, shown in the photo above, is a particularly interesting 
find because it likely has no atmosphere, but does have liquid oceans that are 
essentially lava lakes, she said.

The existence of many small planets in the galaxy that Kepler has found also 
amazed scientists, because there was a possibility that they would have been 
destroyed by larger planets long ago.

"It was a wonderful surprise to see this large number of small planets we have 
found," Borucki said.




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