Earth’s nearest possible habitable planet discovered in Alpha Centauri

24 Aug 2016

Artist's impression of the planet orbiting Proxima Centauri. Image via ESO/M. Kornmesser

After over a week of silence, the European Southern Observatory (ESO) has confirmed ‘clear evidence’ of a rocky planet capable of supporting liquid water in our neighbouring star system, Alpha Centauri.

Located approximately four light years away, the Alpha Centauri star system is our solar system’s nearest stellar neighbour in our galaxy, the Milky Way.

For this reason, astronomers have trained their powerful telescopic eyes towards this region of space with much interest, in the hope of spotting something that could change what we know about our universe.

Discovery confirmed

Now, after a week of silence from the ESO following claims it had discovered a potentially habitable planet in Alpha Centauri, it has confirmed it has finally found “clear evidence” for the existence of a planet it has dubbed Proxima b.

Based on the ESO researchers’ findings on Proxima b, it orbits the solar system’s nearest star, Proxima Centauri, every 11 days and, more importantly, its temperature would allow for liquid water to flow on its surface.

This would make it Earth’s next-nearest potentially habitable planet, thereby making it potentially the closest source of extraterrestrial life in the known universe.

The research, now published in Nature, was conducted by an international team of astronomers called the Pale Red Dot campaign, which first spotted hints of a possible planet orbiting Proxima Centauri.

Proxima b from space

Artist’s impression of the planet orbiting Proxima Centauri. Image via ESO/G. Coleman

Culmination of 30 years of work

But since the beginning of 2016, careful analysis has gradually put the pieces together to reveal the existence of the rocky planet with a mass at least 1.3 times that of the Earth, orbiting about 7m kilometres from its parent star.

Comparing this with our own planet, it would be about 5pc of the distance that exists between Earth and the sun.

While the temperature of Proxima b would allow for liquid water to exist on its surface, the research team added the caveat that conditions on the surface of the planet could still be quite harsh for any lifeforms there.

For example, strong ultraviolet and X-ray flares emitted from Proxima Centauri could make them considerably more intense and deadly that what would be experienced on Earth.

Regardless, this marks a major discovery for astronomy and offers hope of finding similar planets of close proximity to Earth.

Describing it as the culmination of 30 years of work, Pale Red Dot team member Paul Butler said of the discovery: “This work has resulted in the discovery of hundreds of planets around the nearest stars, and now a potentially habitable planet around the nearest star in the sky.

“This work confirms the Kepler satellite and precision velocity studies that have shown that potentially habitable planets are common, and points the way to the future when such planets will be directly observed with giant ground-and-space-based telescopes.”

Starshot into the dark

This discovery will almost certainly add greater impetus for the Breakthrough Starshot mission to send a series of nanocraft to Alpha Centauri at 20pc of the speed of light.

While still very much in a developmental stage, one of the mission’s scientific leads, Prof Avi Loeb, said it will take 20 years for such a craft to travel, allowing researchers to see the star system within a generation.

At that time, however, the mission was just to reach the star system, but now the Starshot craft could be used to analyse Proxima b in unprecedented detail.

Speaking last week, another Starshot team member, Prof Phillip Lubin, said: “The discovery of a 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.”

Colm Gorey was a senior journalist with Silicon Republic