NASA’s Kepler mission has confirmed the first near-Earth-size planet in the “habitable zone” around a sun-like star.
The newly discovered Kepler-452b is the smallest planet to date discovered orbiting in the habitable zone — the area around a star where liquid water could pool on the surface of an orbiting planet — of a G2-type star, like our sun.
The confirmation of Kepler-452b brings the total number of confirmed planets to 1,030.
Nasa also announced it had found another 11 other earth-like planets.
Sarah Knapton discusses Nasa’s latest discoveries with the Video News Editor Olivia Bolton.
The Kepler spacecraft has been looking for signs of new worlds outside the Solar System since May 2009, and has so far found more than 4,000 planets in the so-called ‘Goldilocks Zone’ – neither too hot, nor too cold to sustain life.
The discoveries give new hope that alien civilisations may exist beyond the Solar System.
Earlier this week Professor Stephen Hawking and the Astronomer Royal Lord Martin Rees announced they were joining a $100 million project to seek out signs of extra-terrestrial intelligence in the Milky Way.
There is now clear evidence for huge numbers of nearby planets but many are uninhabitable gas giants or rocky Earth-like planets which are too near their stars to hold life.
Since liquid water is critical to life on Earth, many scientists believe the search for extra-terrestrial life should focus on planets where liquid water occurs.
The size of the planet also means it has enough gravity to pull in gases like hydrogen and helium to form an atmosphere.
Kepler’s task is to look for rocky planets between half and twice the size of Earth where water could still exist on the surface. Nasa is also trying to determine the fraction of the hundreds of billions of stars in our galaxy that might have such planets.
The space observatory detects planets as their orbits cross in front of their star and cause a very tiny but periodic dimming of the star’s brightness.
Last April astronomers found the most Earth-like planet so far orbiting a distant sun in our galaxy.
The planet – named Kepler-186f – is 500 light years away and orbits a red dwarf star in the constellation Cygnus in our corner of the Milky Way.
Kepler-186f is orbiting at the outer edge of the habitable zone around its star, which could mean that any liquid surface water would be in danger of freezing.
However because it slightly larger than Earth scientists are hoping the atmosphere would be thick enough to provide a blanket of insulation.
So far more than 3,800 possible planets have been detected by Kepler but this is the first that is so much like Earth.
However it would be impossible to visit the planet to find out if it contained life. Not only is it 2,939 trillion miles away, the light we are seeing is 500 years old.