Scientists confirm discovery of Earth ‘twin’
Kepler-22b is the planet most akin to our own ever discovered and has a radius that is roughly 2.4 times that of Earth.
The planet is positioned in the “habitable zone” of a star – in a 290-day orbit – which means water could exist on its surface. If the atmosphere of Kepler-22b is similar to that of Earth, its temperature would be about 22C.
Scientists do not yet know if Kepler-22b is predominantly made up of rock, liquid or gas, but say its discovery is a step closer to finding Earth-like planets.
“This is a major milestone on the road to finding Earth’s twin,” said Douglas Hudgins, Kepler program scientist at Nasa headquarters in Washington.
“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.”
Nasa’s Kepler mission has discovered more than 1,000 new planet candidates, ten of which are near Earth-size and orbit in the habitable zone of their host star. These discoveries need to be observed further to determine if they are actual planets.
Natalie Batalha, Kepler deputy science team lead at San Jose State University in California, said: “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.”
“The more data we collect, the keener our eye for finding the smallest planets out at longer orbital periods.”
The Kepler telescope discovers planet candidates by measuring dips in the brightness of more than 150,000 stars, which is seen as an indication of a planet transiting in front of a host star. It requires at least three transits to verify a candidate as a planet.
Fortune smiled upon us with the detection of this planet,” said William Borucki, who led the team that discovered Kepler-22b.
“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 diagram compares our own solar system to Kepler-22, a star system containing the first “habitable zone” planet discovered