Meet Proxima b, a newly discovered exoplanet just four light-years from Earth. Scientists say it could be rocky, watery, and habitable. Should we be optimistic about finding alien life there?
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The ‘Second Earth’ orbiting our nearest star
Meet Proxima b, a newly discovered exoplanet just four light-years from Earth. Scientists say it could be rocky, watery, and habitable. Should we be optimistic about finding alien life there?
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Twenty-five years ago scientists were unsure that they would ever find planets in other solar systems. In 1992The first two exoplanets were discovered orbiting a 'pulsar', a star that died in a supernova. They are part of the Virgo constellation. Three years later, '51 Pegasi b' became the first exoplanet to be found orbiting a star like our own. Since 2009, over 1,000 have been found by NASA's Kepler telescope. two came along at once. Since then they have found over 3,000 - and they now think that there could be tens of billions more scattered throughout the universe.
But this week, a group of scientists announced 'the most important exoplanet discovery there will ever be': a world that could sustain life right next door.
Well, almost. Proxima Centauri is a red dwarf star 25 trillion miles away, but it is our sun's closest star neighbour. Its small size means it gives out far less energy, but the new planet, Proxima b, is right in its 'Goldilocks zone'. That means its orbit is not too hot and not too cold for water to exist on the surface. And where there is water there could also be life.
That is far from a guarantee. Scientists detected the planet by measuring the 'wobbles' in gravity as it orbited its star. They have no idea what it looks like, only that its mass is at least 1.3 times as large as Earth's. That could mean a surface rocky and watery - but alternatively as dry as MarsThe fourth planet from the Sun and the second-smallest planet in the Solar System. , or as inhospitable as Venus.
Then there is the question of an atmosphere. If one exists, it could help warm the planet's temperature up from a chilly -40 degrees C. But Proxima Centauri is a volatile star, giving off flares of radiation that could strip away the planet's surrounding gases.
Scientists also think it could be in a tidal lockThis happens when an orbiting world is close to the object it is orbiting. The most obvious example is the moon, which is locked to Earth., meaning one of its faces always points towards the star - half in day, half in the night, forever.
Despite these caveats, scientists are incredibly excited by the discovery. They do not have the technology to reach the planet yet - but just knowing it is there could be the motivation they need to invent it.
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Could it one day lead them to intelligent life?
Some scientists are hopeful about finding other civilisations out there. They point to the 'Drake equation', a calculation that estimates the likelihood based on the number of planets, the chance of life evolving on each, and so on. Finding a habitable planet just one star over is good news; even if it does not host life, it suggests that there are billions more that might. With so many planets to explore, how could we be alone?
Others are sceptical. Consider another thought experiment, known as 'Fermi's Paradox', summarised in just three words: where is everybody? If alien civilisations really did exist, surely we would have found them by now - or vice versa? Scientists have been searching for centuries; but no matter how advanced their technology gets, they never find anyone. We must admit that the universe is a lonely place, and be grateful for our amazing home in it.
Keywords
1992 - The first two exoplanets were discovered orbiting a 'pulsar', a star that died in a supernova. They are part of the Virgo constellation. Three years later, '51 Pegasi b' became the first exoplanet to be found orbiting a star like our own. Since 2009, over 1,000 have been found by NASA's Kepler telescope.
Mars - The fourth planet from the Sun and the second-smallest planet in the Solar System.
Tidal lock - This happens when an orbiting world is close to the object it is orbiting. The most obvious example is the moon, which is locked to Earth.
The ‘Second Earth’ orbiting our nearest star
Glossary
1992 - The first two exoplanets were discovered orbiting a 'pulsar', a star that died in a supernova. They are part of the Virgo constellation. Three years later, '51 Pegasi b' became the first exoplanet to be found orbiting a star like our own. Since 2009, over 1,000 have been found by NASA's Kepler telescope.
Mars - The fourth planet from the Sun and the second-smallest planet in the Solar System.
Tidal lock - This happens when an orbiting world is close to the object it is orbiting. The most obvious example is the moon, which is locked to Earth.