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THE probability we are alone in the universe was slashed after NASA revealed there could be as many as 10 billion Earth-like exoplanets, potentially harboring life in our own Galaxy, The Milky Way, ALONE.

Yesterday, the US space agency announced there are 2,325 confirmed planets in just a tiny fraction of the galaxy studied by the Kepler Telescope mission.

Exoplanets are those which orbit a star in the so-called Goldilocks or habitable zone, where the distance from the sun means it is not too hot nor too cold to stop life forming.

Now NASA has estimated there are tens of billions of these in the Milky Way and many of them could be small and rocky like Earth.

It has also revealed a further two so called "Earth 2" planets which are like ours and at just the right distance from their stars for life to evolve.

Natalie Batalha, Kepler mission scientist at NASA's Ames Research Center in Moffett Field, California, has now estimated just how many exoplanets, and more importantly ones similar to Earth orbiting their star at the right distance, there are likely to be in the whole of The Milky Way.

Ms Batalha said there are an estimated 100 billion stars across the galaxy, but based on Kepler statistics around three quarters of these could be ruled out as having any planets anything like ours.

However, she said a solid 25 per cent of stars in the Milky Way WERE likely to have small, rock-formed planets orbiting a star at a distance making them the right temperature for life to potentially evolve.

She said: "Twenty five per cent of solar systems could potentially harbour smaller, rocky planets like Earth.
"There could be 10 billion potentially habitable planets in our galaxy, that is my back of an envelope calculation."
The implications for the number of Earth-like planets in the millions of other galaxies in the universe is startling. Asked what the closest likely contender was, she said it would take around 11 years to reach if travelling at the speed of light were possible. She said: "The nearest would be within about 11 light years, which, astronomically speaking is very close."
Data from the Kepler Telescope, which works out if planets are orbiting stars by looking for tiny dips in light as the planet passes the sun, is still being analysed.

But a series of new space probe missions are being launched over the next few years to try to shed more light on whether we have any nearest neighbors.
Paul Hertz, director of the Astrophysics Division at NASA Headquarters, said: "Before the Kepler space telescope launched, we did not know whether exoplanets were rare or common in the galaxy.
"Thanks to Kepler and the research community, we now know there could be more planets than stars. "This knowledge informs the future missions that are needed to take us ever-closer to finding out whether we are alone in the universe."
In late 2017 the Transiting Exoplanet Survey Satellite (TESS) will be launched to survey the entire sky looking for planets around our 200,000 closest stars.

In October 2018 the James Webb Space Telescope is scheduled to go up to carry out intensive studies of light being emitted by neighbouring stars and look at how it reaches planets outside our solar system.

The European Space Agency is sending up its own specialist probe in the 2020s that will get more exact locations for planets in relation to their stars.

So far, of the estimated 10 billion Earth-like planets, four have caught the eye of NASA experts as being the most Earth-like, dubbed Earth 2s, and therefore capable of holding lifeforms if they evolved.

Two of these, known as Kepler 452b and Kepler 186f, were revealed last year and 2014 respectively.

But Ms Batalha said a further two Earth 2s were identified during the latest studies.
She said: "These have interested me the most. Kepler 1229b is Earth-sized and in the middle of the habitable zone.
"And Kepler 1638b. It is 50 per cent larger than Earth, but it orbits a sun that is warmer than our sun."
This is critical because if Earth was half as big again, but orbiting our sun at the same distance, it would likely be too big to warm up enough for life to start, but a warmer sun could, in contrast possibly achieve that.
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Earth-like Planets



Milky way

Solar system


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