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The results of the Pale Red Dot campaign
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— the quest to find a planet
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orbiting the closest star to the Solar System —
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have now been announced.
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Astronomers have found clear evidence
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of a planet orbiting the star Proxima Centauri.
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This alien world is the closest possible abode
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for life outside the Solar System!
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This is the ESOcast!
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Cutting edge science and life behind the scenes at ESO,
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the European Southern Observatory.
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The search for other worlds has captivated
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imaginations throughout history,
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but only recently have we had the instruments
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able to detect worlds outside the Solar System.
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These extrasolar planets, or exoplanets,
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went undetected until 25 years ago.
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Today, thanks to advances in telescope technology,
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astronomers have detected over three thousand.
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And now the scientists behind
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the Pale Red Dot campaign
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have made a milestone discovery.
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They have discovered clear evidence for
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a potentially habitable planet orbiting Proxima Centauri,
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the closest star to the Solar System.
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Using the HARPS spectrograph
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on ESO’s 3.6 metre telescope at La Silla in Chile,
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astronomers spent the first half of 2016 looking
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for the tiny back and forth wobble of the star
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caused by the gravitational pull of an orbiting planet.
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They were trying to build on 16 years
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of earlier observations
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that hinted of the presence of a planet,
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but were inconclusive.
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Combining the data with observations
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from a network of telescopes around the world,
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the researchers confirmed
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the detection of an alien world.
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It’s at least 1.3 times as massive as the Earth
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and orbits Proxima Centauri every 11.2 days.
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It was no easy task to identify the planet, however.
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Red dwarfs like Proxima Centauri
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are active stars prone to flares,
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and can vary in ways that would
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mimic the presence of a planet.
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To exclude this possibility,
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the team carefully monitored the brightness of the star
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with a network of telescopes
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to ensure they didn’t misidentify such an important discovery.
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Perhaps the most exciting aspect of this research
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is that the exoplanet, called Proxima b,
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orbits within the habitable zone of its star.
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This means that liquid water could exist
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on the planet’s surface.
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If it were much closer the heat from the star
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would boil the water away.
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And if it were further out
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the planet’s water would freeze solid.
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Since liquid water is essential for life as we know it,
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this makes Proxima b the closest exoplanet
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to Earth that may harbour life.
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However, the same stellar activity that made Proxima b
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so difficult to spot
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could also make it an inhospitable abode for life —
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the planet’s surface is bathed
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by intense ultraviolet and X-ray radiation.
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The planet also orbits
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Proxima Centauri extremely closely,
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only 5% of the Earth Sun distance.
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It is still a matter of debate whether a planet
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so close to its star could support life.
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Proxima b’s closeness to the Earth
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makes it an intriguing target
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in the search for extraterrestrial life.
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Astronomers will use the next generation
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of telescopes
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such as ESO’s European Extremely Large Telescope
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to make an intensive study
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of this fascinating alien world
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in the hope of finding evidence of life
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elsewhere in the Universe.
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And if interstellar probes become a reality
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Proxima b may be their first destination.
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Scientific knowledge of exoplanets has grown
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has grown hugely in the last 25 years.
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With this discovery,
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and armed with ESO’s next generation telescope,
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we may soon be within reach
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of answering the age old question —
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are we alone?
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Transcription by ESO; translation by —
