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Kepler 22b - a planet in a star's habitable zone

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Uploaded on Dec 13, 2011

Astronomers announced the discovery of Kepler 22b, a planet orbiting a star not unlike our own sun at a distance where life can thrive.

The discovery was announced by a team of astronomers using the Kepler Space Telescope. Launched in 2009, Kepler's sole purpose is to hunt for earth like worlds around other stars. Unlike other telescopes, Kepler stares unblinkingly at a region of the sky in the constellation of Cygnus the Swan. It's 95 megapixel camera monitors 150,000 stars in its field of view.

But earth-like planets are impossible to directly image using our best telescopes; they are simply lost in the glare of their parent stars.

Instead, Kepler monitors the slightest of changes in brightness of the star as its planet transits in front of it during its orbit.

Using this technique, Kepler has discovered 28 exoplanets, and as many as 1500 possible new worlds are awaiting confirmation.

Over time, the light from Kepler 22 briefly flickered by 1/2 of 1/1000 of a percent once every 290 days. Astronomers quickly understood that this was a planet within Kepler 22's habitable zone.

A habitable zone is a range of distances around a star where the temperature is neither too hot, nor too cold, to support life. A habitable zone around a hotter star would be farther out, while a habitable zone around a cooler star would be closer in. Given any star's temperature, there is an orbit where the temperature is just right for life.

Kepler 22b's orbital period places the planet within Kepler 22's habitable zone. The star at Kepler 22 is almost identical to our sun, just 220K cooler, so its habitable zone is slightly closer, making Kepler 22b a strong candidate for finding life.

Kepler 22b is 2.4 times the diameter of earth, placing it somewhere between earth and neptune in size. But so far we know nothing else about this world; not its composition, or if it even has an atmosphere inside of which life could survive.

To answer these questions, astronomers will need to use different types of telescopes at optical and infrared wavelengths to determine what kind, if any, atmosphere exists at Kepler 22b.

At 600 light years away, we will not be able to visit Kepler 22b anytime soon to see for ourselves if life really does exist there.

But that hasn't stopped the SETI institute from using the Allen Telescope Array from listening in for any possible artificial signals coming from Kepler 22b...just in case.

Meanwhile, the hunt for earthlike worlds continues with the Kepler telescope, and an ever-growing archive of data is being produced. And we need your help sorting through it.

Planethunters.org is a site where anyone can log in to examine Kepler's data, and help identify the telltale signal of orbiting planets.

Could Kepler 22b really be a second Earth? That remains to be seen. But what is truly remarkable is that we are now able to detect worlds orbiting within stars' habitable zones. Kepler 22b is only the first of many more such worlds surely to be discovered. Life-bearing planets have long been speculated; Kepler 22b is a major step toward knowing they truly exist.

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