Kepler spies most Earth-like planet yet

Astronomers have found a close cousin of the Earth – a rocky planet circling its star in the “Goldilocks zone” where it is not too hot nor too cold to support liquid water, NASA says.

What’s more the planet’s star looks similar to our Sun, albeit at 6 billion years, a 1.5-billion-year older version.

The planet has been named Kepler 452b and is 1,400 light years away. It was detected by NASA’s Kepler Space Telescope, which has been hunting for planets similar to the Earth since 2009.

Its similarity to Earth, combined with the age of the star, may give scientists some insights into what lies in store for our planet as an ageing Sun heats up a billion years from now, with massive heating leading to lakes and oceans evaporating. 

“If Kepler 452b is indeed a rocky planet, its location vis-a-vis its star could mean that it is just entering a runaway greenhouse phase of its climate history,” said Doug Caldwell, a Search for Extraterrestrial Intelligence (SETI) Institute scientist working on the Kepler mission, told ABC news.

The Kepler mission launched in 2009 to search for exoplanets, which are planets outside our solar system, particularly those about the size of Earth or smaller.

NASA’s latest catalogue of exoplanet candidates consists of 4,675 discovered by the telescope.

This size and scale of the Kepler-452 system compared alongside the Kepler-186 system and our solar system. Kepler-186 is a miniature solar system that would fit entirely inside the orbit of Mercury. The habitable zone of Kepler-186 is very small compared to that of Kepler-452 or the sun because it is a much smaller, cooler star. The size and extent of the habitable zone of Kepler-452 is nearly the same as that of the sun, but is slightly bigger because Kepler-452 is somewhat older, bigger and brighter.
NASA/JPL-CalTech/R. Hurt

Kepler-452b is 60% larger in diameter than Earth. Scientists are yet to determine its mass and composition but previous research suggests that a planet its size should be rocky. Its orbit of 385 days is similar to an Earth-year. 

“We can think of Kepler-452b as an older, bigger cousin to Earth, providing an opportunity to understand and reflect upon Earth’s evolving environment,” said Jon Jenkins, Kepler data analysis lead at NASA’s Ames Research Center in Moffett Field, California, who led the team that discovered Kepler-452b.

“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.”

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