Monday, 5 December 2011

Earth-like planet found in distant sun's habitable zone

For the first time, astronomers using NASA's Kepler space telescope have confirmed a roughly Earth-size planet orbiting a sun-like star in the so-called "Goldilocks" zone where water can exist in liquid form on the surface and conditions may be favorable for life as it is known on Earth.

Along with the confirmed extra-solar planet, one of 28 discovered so far by Kepler, researchers today also announced the discovery of 1,094 new exoplanet candidates, pushing the spacecraft's total so far to 2,326, including 10 candidate Earth-size worlds orbiting in the habitable zones of their parent stars.

Additional observations are required to tell if a candidate is, in fact, an actual world. But astronomers say a planet known as Kepler-22b, orbiting a star some 600 light years from Earth, is the real thing."Today I have the privilege of announcing the discovery of Kepler's first planet in the habitable zone of a sun-like star, Kepler-22b," Bill Borucki, the Kepler principal investigator at NASA's Ames Research Center, told reporters. "It's 2.4 times the size of the Earth, it's in an orbital period (or year) of 290 days, a little bit shorter than the Earth's, it's a little bit closer to its star than Earth is to the sun, 15 percent closer.

"But the star is a little bit dimmer, it's a little bit lower in temperature, a little bit smaller. That means that planet, Kepler-22b, has a rather similar temperature to that of the Earth...If the greenhouse warming were similar on this planet, its surface temperature would be something like 72 Fahrenheit, a very pleasant temperature here on Earth."

It is not yet known whether Kepler-22b is predominantly rocky, liquid, or gaseous in composition, but the finding confirms for the first time the long-held expectation that Earth-size planets do, in fact, orbit other suns in the habitable zones of their host stars.

That, in turn, greatly improves the odds for the existence of life, as it is commonly defined, beyond Earth's solar system.

No comments:

Post a Comment