ASTRONOMERS are preparing to announce the discovery of a potentially habitable second Earth orbiting a nearby star, it has been claimed.

Last month, sources leaked news that the European Southern Observatory (ESO) had spotted an alien world orbiting Proxima Centauri, our closest stellar neighbour.

An anonymous source from the ESO told German publication Der Spiegel the discovery is the closest habitable planet to Earth, which means we could reach it within our lifetime.

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2 It is not yet known whether the second Earth could support living organisms Credit: NASA

But the astonishing finding was not officially announced, sparking furious speculation that the second Earth has deliberately been kept a secret.

Now the ESO is set to finally reveal details of the planet at a press conference tomorrow and astronomers are also likely to discuss whether it has the potential to support life.

“The still nameless planet is believed to be Earth-like and orbits at a distance to Proxima Centauri that could allow it to have liquid water on its surface — an important requirement for the emergence of life,” the source said.

“Never before have scientists discovered a second Earth that is so close by.”

Since its launch in 2009, NASA’s planet finding Kepler Spacecraft has discovered more than 4000 exoplanet candidates.

Of these, there have been 216 Earth-like located within the Goldilocks Zone — the region around a star in which the surface temperature of an orbiting planet might support water.

The problem is that while most of these Earth-like planets are habitable, they are located thousands of light years away, which means they are out of our reach.

Astronomers from the observatory had previously claimed to have found the then-closest exoplanet to Earth in 2012, although subsequent analysis cast doubt on its existence.

2 A shot of Promixa Centauri snapped by the Hubble Telescope

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Despite this misstep, the unnamed source claim this latest discovery is authentic and the result of intensive work.

“Finding small celestial bodies is a lot of hard work,” the source said.

“We were moving at the technically feasible limit of measurement.”

If the findings are correct, Russian billionaire Yuri Milner’s search for intelligent life could focus on heading to the planet.

As part of Milner’s plans, Project Starshot intends to send a laser-sail driven-nanocraft to Alpha Centauri — the closest star system to the Solar System — in the coming years.

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With the craft able to travel up to 20 per cent of the speed of light, if Project Starshot was to rethink its objective, it would be able to reach the Earth-like planet orbiting Proxima Centauri in less than 20 years.

However, mastermind of Project Starshot Professor Phillip Lubin said the focus will likely stay on Alpha Centauri.

“The discovery of possible planet around Proxima Centauri is very exciting. It makes the case of visiting nearby stellar systems even more compelling, though we know there are many exoplanets around other nearby stars and it is very likely that the Alpha Centauri system will also have planets,” he told Universe Today.

The European Southern Observatory are expected to officially announce the finding at the end of August.