Kepler-452b is first smallest planet found orbiting in the habitable zone
- The planet has same size orbit as Earth, and the same length of year
- Scientists say they are not yet sure whether the planet hosts alien life
- But they said if plants were transferred to the planet, they may survive
- Kepler has also found 12 other small habitable zone candidate planets
Astronomers have found the first near-Earth-size planet that could host alien life.
Named Kepler-452b, it is the smallest planet to date discovered orbiting in the habitable zone of a G2-type star, like our sun.
The Earth-like world has a 'substantial opportunity' to host life, Nasa says, adding that if plants were transferred there, they would likely survive.
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This artist's concept depicts one possible appearance of the planet Kepler-452b, the first near-Earth-size world to be found in the habitable zone of star that is similar to our sun. The habitable zone is a region around a star where temperatures are right for water - an essential ingredient for life as we know it - to pool on the surface
The planet is about 60 per cent bigger than Earth, is located about 1,400 light years away in the constellation Cygnus.
Its discovery brings the total number of confirmed planets to 1,030.
Nasa has also found 12 new small habitable zone candidate planets, marking another milestone in the journey to finding another 'Earth.'
'This exciting result brings us one step closer to finding an Earth 2.0,' said John Grunsfeld, associate administrator of Nasa's Science Mission Directorate.
Kepler-452b is larger than Earth, but its 385-day orbit is only 5 per cent longer.
It resides in something known as the habitable zone - or Goldilocks zone - which is an area around a star where liquid water could pool on the surface of an orbiting planet.
It is fiveper cent farther from its parent star Kepler-452 than Earth is from the sun.
Kepler-452 is 6 billion years old, 1.5 billion years older than our sun, has the same temperature, and is 20 per cent brighter and has a diameter 10 per cent larger.
Kepler-452b is 60 per cent larger in diameter than Earth and is considered a super-Earth-size planet.
While its mass and composition are not yet determined, previous research suggests that planets the size of Kepler-452b have a good chance of being rocky.
'We can think of Kepler-452b as an older, bigger cousin to Earth,' said Jon Jenkins, Kepler data analysis lead at Nasa's Ames Research Center.
An artist's impression of exoplanet Kepler-452b, which Nasa say is likely to be rocky, just like Earth
The artistic concept compares Earth (left) to the new planet, called Kepler-452b, which is about 60 percent larger. The illustration represents one possible appearance for Kepler-452b - scientists do not know whether the planet has oceans and continents like Earth
Kepler-452 is 6 billion years old, 1.5 billion years older than our sun, has the same temperature, and is 20 per cent brighter and has a diameter 10 per cent larger
'It's awe-inspiring to consider that this planet has spent 6 billion years in the habitable zone of its star' longer than Earth.
'That's substantial opportunity for life to arise, should all the necessary ingredients and conditions for life exist on this planet.'
To help confirm the finding and better determine the properties of the Kepler-452 system, the team conducted ground-based observations.
These measurements were key for the researchers to confirm the planetary nature of Kepler-452b, to refine the size and brightness of its host star and to better pin down the size of the planet and its orbit.
The planet is 5 per cent farther from its parent star Kepler-452 than Earth is from the sun, Nasa has said
This size and scale of the Kepler-452 system compared alongside the Kepler-186 system and the solar system. Kepler-186 is a miniature solar system that would fit entirely inside the orbit of Mercury
The first exoplanet orbiting another star like our sun was discovered in 1995. Exoplanets, especially small Earth-size worlds, belonged within the realm of science fiction just 21 years ago. Today, astronomers are on the cusp of finding something people have dreamed about for thousands of years - another Earth
The research paper reporting this finding has been accepted for publication in The Astronomical Journal.
In addition to confirming Kepler-452b, the Kepler team has increased the number of new exoplanet candidates by 521 from their analysis of observations conducted from May 2009 to May 2013, raising the number of planet candidates detected by the Kepler mission to 4,696.
Candidates require follow-up observations and analysis to verify they are actual planets.
Twelve of the new planet candidates have diameters between one to two times that of Earth, and orbit in their star's habitable zone.
Of these, nine orbit stars that are similar to our sun in size and temperature.
'We've been able to fully automate our process of identifying planet candidates, which means we can finally assess every transit signal in the entire Kepler dataset quickly and uniformly,' said Jeff Coughlin, Kepler scientist at the SETI Institute in Mountain View, California.
The habitable zone is the area around a star where liquid water could pool on the surface of an orbiting planet. The confirmation of Kepler-452b brings the total number of confirmed planets to 1,030
The Kepler Space Telescope, shown in the artists impression above, has discovered 1,028 confirmed exoplanets since launching in 2009. Astronomers have moved its position of view regularly (shown by the crosses in the image, to watch for tiny changes in brightness from stars that may indicate an orbiting planet
'This gives astronomers a statistically sound population of planet candidates to accurately determine the number of small, possibly rocky planets like Earth in our Milky Way galaxy.'
These findings, presented in the seventh Kepler Candidate Catalog, will be submitted for publication in the Astrophysical Journal.
Last year astronomers announced the telescope had spotted its first Earth-sized planet in the habitable zone of another star.
Kepler-186f, which is around 500 light years from Earth, was the first planet to be discovered that is reminiscent of our own.
In January Nasa announced another two new planets - Kepler 438b, which is thought to be only 12 per cent bigger than Earth, and Kepler-442b, which is thought to be 33 per cent bigger.
In July, Kepler spotted five planets orbiting around the same star - Kepler-444 - all of which are thought to be close to the size of Earth.
Paul Hertz, director of astrophysics at Nasa, said identifying worlds that could be home to alien life with Kepler would allow future missions to look at them more closely.
He said: 'Future Nasa missions, like the Transiting Exoplanet Survey Satellite and the James Webb Space Telescope, will discover the nearest rocky exoplanets and determine their composition and atmospheric conditions, continuing humankind's quest to find truly Earth-like worlds.'
Twelve of the new planet candidates have diameters between one to two times that of Earth, and orbit in their star's habitable zone
The sweep of Kepler mission’s search for small, habitable planets in the last six years. The first planet smaller than Earth, Kepler-20e, was discovered in December 2011 orbiting a sun-like star slightly cooler and smaller than our sun every six days. But it is scorching hot and unable to maintain an atmosphere or a liquid water
