Astronomers have discovered what they believe to be the closest habitable planet to Earth

An anonymous source said the discovery is the closest habitable planet to Earth, which means we could reach it within our lifetime. Photo / Getty Images

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.

However, using a reflecting telescope at the European Southern Observatory (ESO), astronomers have recently discovered exoplanet orbiting Proxima Centauri - a red dwarf, a small low-mass star about 4.25 light-years from the Sun.

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.

"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."

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.

Despite its sketchy track record, 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.

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 toldUniverse Today.

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