The discovery was made by a NASA planet-hunting telescope

Dec 6, 2011 07:35 GMT  ·  By

Astronomers operating the NASA Kepler Telescope announce the discovery of the first extrasolar planet orbiting inside its parent star's habitable zone. The object is called Kepler-22b, and can be found in an area of its star system where temperatures are just right to support the presence of liquid water.

This is not the first time that such an object is proposed, but definitely the first time the proposal is confirmed and verified by independent studies. In addition to Kepler-22b, the telescope also identified 10 candidates that are about the size of Earth, and also orbit inside their stars' habitable zones.

In addition, the observatory's science team has also revealed a list of about 1,094 exoplanetary candidates, in addition to the 1,235 it already proposed when its first batch of data were made public.

This raises the total number of proposed exoplanetary candidates to more than 2,300 from the Kepler Telescope alone. Ground-based observatories and other space assets now have their hands full in trying to independently confirm these discoveries. The process will take a while.

As for Kepler-22b, the planet has a radius about 2.4 times that of Earth, and orbits its parent star in about 290 days. The star Kepler-22 is a G-type object similar to our Sun, and is located some 600 light-years away from our planet.

The object is only slightly smaller and cooler than our Sun, and its planet is also a bit closer to it than Earth is from our parent star. Additional details of the system will be published in an upcoming issue of the esteemed Astrophysical Journal.

One of the most important things that still remain to be discovered about Kepler-22b is whether it has a rocky, liquid or gaseous composition. This has not yet been established with any degree of certainty, but astronomers are convinced that additional studies will shed light on this mystery.

“This is a major milestone on the road to finding Earth's twin. Kepler's results continue to demonstrate the importance of NASA's science missions, which aim to answer some of the biggest questions about our place in the Universe,” Douglas Hudgkins explains.

The official holds an appointment as a Kepler program scientist at NASA Headquarters, in Washington.

“Fortune smiled upon us with the detection of this planet. 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,” adds William Borucki.

The scientist – who is based at the NASA Ames Research Center, in Moffett Field, California – is the principal investigator for the Kepler Telescope, and also the leader of the team that discovered this promising exoplanet.

Out of a total of 2,326 exoplanetary candidates, 1,181 are the size of Neptune, 203 the size of Jupiter, 55 larger than Jupiter, 680 are of the super-Earth class, and the remaining 207 are about the size of Earth.

What is also interesting to note is that the new batch of exoplanetary candidates was derived from observations conducted between May 2009 to September 2010. As opposed to the first batch of data, the second one features significantly higher numbers of smaller planets.

At the same time, the latest dataset includes 48 candidates that may orbit inside their stars' habitable zones. Though the number is smaller than the one published in the first Kepler dataset, 54, it is more precise, since the definition of habitable zones was further refined in the meantime.

“The tremendous growth in the number of Earth-size candidates tells us that we're honing in on the planets Kepler was designed to detect: those that are not only Earth-size, but also are potentially habitable,” investigator Natalie Batalha says.

“The more data we collect, the keener our eye for finding the smallest planets out at longer orbital periods,” concludes the scientist, who is the deputy leader of the Kepler science team, at the San Jose State University, in California.

Photo Gallery (2 Images)

Artist's rendition of exoplanet Kepler-22b
Diagram comparing the solar system to the Kepler-22 star system. The latter contains Kepler-22b, the first planet discovered inside its parent star's habitable zone
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