A-Proxima-tely alone

James McCoul analyses whether there's life out there

James McCoull
22nd February 2017

The possibility of life elsewhere in the universe is one that has fascinated humanity for its entire lifespan – from the planetary deities of the Roman pantheon to 20th century science fiction's preoccupation with every form of alien life imaginable. Now though, exoplanet hunters are seriously considering that possibility on a place not so far from home.

Proxima B is a planet orbiting the aptly named red dwarf Proxima Centauri – the nearest star to our own sun at just 4.25 light years. Needless to say, that's still an unfathomable distance in human terms (over 24 trillion miles, in fact) but in cosmic terms it's very close indeed. So why Proxima B? The salient facts are these: it's an Earth-size planet orbiting Centauri at a distance suggesting habitability to organic lifeforms. Details of its atmosphere and even its surface are unknown, though; it could well be composed of gases or liquids rather than any kind of solid matter at all, and that's before you get into any of the other myriad requirements for a life-bearing planet (a 'garden world', to borrow a science fiction term).

Proxima B is a planet orbiting the aptly named red dwarf Proxima Centauri – the nearest star to our own sun at just 4.25 light years

That said, the discovery team is optimistic. Apparently, initial data is suggestive of a terrestrial planet, a 'surface you can stand on' in the words of the team, and its proximity to Centauri would allow for water to exist in a liquid state. The implications of this are twofold: firstly, that human beings might be able to live there, assuming the technology to traverse the vast distance was developed at some point, and secondly that if they did so they might not be alone when they arrived. Current estimates suggest that an unmanned probe travelling to Proxima Centauri at 17 kilometres a second (the velocity of the Voyager 1 probe) would take more than 17,000 years to arrive, and needless to say the human race it had left behind would be in a very different state when it arrived; given sufficient advances in technology, we might expect to beat it there by a wide margin. Better means of propulsion could get an unmanned probe there much faster: the Breakthrough Starshot project is currently working on getting a probe to Alpha Centauri, a neighbouring system, but the possibility of getting living people across such a span is still a distant dream.

Those are the pessimistic realities of the situation, but there's still plenty to be excited about. Having a feasibly habitable exoplanet so close (relatively speaking) to our own is a fantastically lucky happenstance, as the probability of a planet sustaining life when considering all the relevant factors is incredibly low. This is, of course, when using a fairly restrictive definition of life as we know it, and there's no way of guessing what else might actually exist out there. Details as to the precise nature of Proxima B are scarce for the time being. However, following its discovery by scientists at the La Silla Observatory in Chile, it is feasible that observations could be made concerning wavelengths of light passing through the exoplanet's atmosphere which would form the grounds for conclusions about the chemical composition of the planet itself. Other potential projects include the application of the 'European Extremely Large Telescope' currently in development, which might be able to analyse specific details about the planet's atmosphere (if indeed there is one to analyse).

Details are scarce and all conclusions are extremely tentative, but that's to be expected with a discovery such as this. For the time being, all we can do is monitor the situation and wait for technology to catch up to our interstellar ambitions. That is, unless anything that might be living out by Proxima Centauri gets to us first.

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