Evidence of life on Proxima B ‘could be uncovered within a few years’

Proxima b (Credit: PHL @ UPR Arecibo, NASA EPIC team)
Proxima b (Credit: PHL @ UPR Arecibo, NASA EPIC team)

Evidence of alien life on Proxima b, the newly-discovered planet orbiting the closest star to Earth, could emerge within a few years, scientists believe.

New telescope technology holds out the hope of spotting oxygen generated by vegetation growing on the planet's surface.

Clear signs of life on Proxima b would be one of the greatest scientific discoveries of all time.

The planet orbits Proxima Centauri, a faint red dwarf star just 4.27 light years from Earth.

It is part of a triple system of stars which also includes the much brighter pair Alpha Centauri A and B. From Earth, the system appears as a single bright star - the third brightest visible in the night sky.

Astronomers led by a British team from Queen Mary, University of London, announced the discovery of Proxima b last week in the journal Nature.

The planet is thought to be about 1.3 times more massive than Earth and probably rocky. It lies within its star's "habitable zone" where temperatures are just right to allow the existence of liquid surface water, raising the possibility of life.

If the planet formed further out from its star before migrating to its present close position just 7.5 million kilometres away (4.6 million miles), it could have deep global oceans.

Astronomers, geophysicists, climatologists and biologists are now working together to ponder the possibility of life on Proxima b.

Leading University of Washington astronomer Dr Rory Barnes wrote in a blog for the palereddot.org website, which is dedicated to the new planet: "The short answer is, it's complicated. Our observations are few, and what we do know allows for a dizzying array of possibilities."

The biggest obstacle to life on Proxima b is the fact that it is 25 times closer to its star than the Earth is to the Sun.

Because the star is so faint, temperatures on its surface would still be mild. But the planet could be blasted by radiation from solar flares, and may be gravitationally "locked" with one face always pointing towards the star.

The answer could be provided by a new method of measuring oxygen in an exoplanet's atmosphere invented at the University of Washington.

At sufficient pressures, oxygen molecules can briefly bind together to produce an observable light signal strong enough to be detected by telescopes.

Research has shown that only photosynthesis by plants is likely to produce this kind of signal.

Once the technology is fully developed it could enable the powerful new James Webb Space Telescope, due to be launched in 2018, to search for life on Proxima b.

Since Proxima Centauri has an expected lifespan trillions of years longer than that of the Sun, it could provide a secure future for the human race, scientists believe.

Dr Barnes wrote: "If Proxima b is habitable, it might be an ideal place to move. Perhaps we have just discovered a future home for humanity."