Proxima b: Scientists discover a new Earth 2.0 just four light years away

The rumours were indeed correct: scientists from the European Southern Observatory have announced an exoplanet that looks encouragingly similar to Earth, and it’s right on our galactic doorstep. 

Proxima b: Scientists discover a new Earth 2.0 just four light years away

Announcments like this have come before. Remember last year when NASA announced an Earth 2.0 and everyone got really excited? It seemed from where we were sitting to be near-identical to Earth, and have conditions — potentially — ripe for life. One tiny fly in the ointment: it’s 1,400 light years away, meaning it would take New Horizons around 25.8 million years — give or take — to get there and check it out for us. Most people just don’t have that kind of patience.

“Alpha Centauri is some 24,792,710,570,270 miles away, meaning New Horizons would need an extra 77,990 years to make the journey”

But Proxima b is a lot closer to home: just 4.25 light years away, in the Alpha Centauri system. Better still, it seems to be a rocky planet, like Earth, and is close enough to its star – a red dwarf called Proxima Centauri – for liquid water to exist. In other words, it could be ripe for alien life.

Hopefully, anyway. Although it’s similar sounding to Earth on paper, the planet is exposed to a lot of ultraviolet rays and X-rays. That doesn’t rule out life, but it means that any that has evolved will have learned to cope with the hostile conditions.

Poxima b – a planet of 1.3 times the mass of Earth – is just 7.5 million kilometres from the star it orbits, which is a lot closer than we are to the sun. But said star, Proxima Centauri is a red dwarf meaning it’s significantly dimmer, so life can’t be ruled out.

Still, much of this is intelligent guesswork. Proxima b was uncovered using HARPS – a spectrograph attached to a 3.6m telescope at the La Silla observatory in Chile. The planet was confirmed by a “wobble” a star undergoes when a gravitational bound planet circles it – which in the case of Proxima b happens once every 11.2 days. 

Dr Guillem Anglada-Escude from Queen Mary University of London, who led an international team of astronomers said, “Succeeding in the search for the nearest terrestrial planet beyond the solar system has been an experience of a lifetime, and has drawn on the dedication and passion of a number of international researchers.

“We hope these findings inspire future generations to keep looking beyond the stars. The search for life on Proxima b comes next.”


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4.25 light years is only close to us in relative terms. New Horizons is the fastest spacecraft ever built, and it still took nine and a half years to reach Pluto, which is just 327 light minutes away. To put things into perspective, Alpha Centauri is some 24,792,710,570,270 miles away, meaning the plucky little ship would need an extra 77,990 years to make the journey. Though scientists are exploring other options.

Nonetheless it’s proximity means that we can study it far more easily, which makes a huge difference. The information we know about other Earth-like planets is based on plenty of guesswork, because they’re too far away to see, even with our strongest telescopes. What we know about Kepler-452b, for example, is inferred from the weak shadow observed when it passes its star.

Proxima b will be the subject of far more study over the next few years, and the timing of the discovery is pretty good. We’re just two years away from the expected launch of the James Webb telescope, which is 100 times more powerful than the Hubble. 

Even on the scant details we have right now, it’s hard to understate how exciting this is. As Dr Carole Haswell from Open University told the BBC, “I think it’s the most important exoplanet discovery there will ever be – how can you ever trump something that could be habitable orbiting around the very closest star to the Sun?”

Images: Hubble ESA and ESO used under Creative Commons

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