A second earth discovered

The existence of an Earth-like planet has been confirmed by astronomers. Kepler 22-b has been discovered to be orbiting a star not unlike our Sun, located approximately 600 light years away. It is around 2.4 times the size of Earth and has a temperature of about 22C. Despite it’s resemblance to Earth, the Keplar team are as of yet unsure whether Kepler 22-b is made of rock, gas or liquid.

In contrast to Earth, Kepler 22-b is located 15% closer to its Sun and so its year lasts for 290 days. However, in contrast to our Sun, the planet’s host star emits 25% less light and so Kepler 22-b remains at a mild temperature. This would allow for the existence of liquid water.
The confirmation of Kepler 22-b was announced at the recent Kepler Conference. This confirmation follows on from a report made by the Kepler team in February, in which the team detailed 54 exoplanet candidates in habitable zones. A recent redefinition of the habitable zone’s boundaries has reduced this number to 48. Ten of those are Earth sized and it is likely that more of these candidates will be confirmed in the future.

At the conference the Kepler team also went into greater detail about other discoveries made. The team discussed some 1,094 candidate planets that were identified, showing the vast expanse that the telescope now reaches. In total, 2.326 candidates have now been spotted by the Kepler space telescope. 207 of these are said to be Earth sized.

The Kepler space telescope’s impressive design looks at a fixed section of the night sky, focusing specifically on around 150,000 stars. The advanced nature of this telescope means that it is receptive enough to see when a planet passes in front of its host star, a movement that dims the star’s light by a miniscule amount. The Kepler telescope, along with other telescopes in orbit and on earth, classifies these tiny reductions in starlight as candidate planets.

With the Kepler 22-b, the team waited for the planet to pass its host star 3 times before changing the status from ‘candidate’ to ‘confirmed’. William Borucki, Kepler principal investigator at Nasa’s Ames Research Center said: "The first transit was captured just three days after we declared the spacecraft operationally ready. We witnessed the defining third transit over the 2010 holiday season."

This is exciting news for the Search for Extraterrestrial Intelligence (Seti). Jill Tarter, the director of the Center for Seti Research at the Seti Institute comments: "This is a superb opportunity for Seti observations” as the ongoing hunt for extraterrestrial intelligence is narrowed.

Published: Thursday, 8th December 2011 by Kate Foreman