Becoming the closest confirmed ‘exoplanet’ in a wider US-European competition to find the nearest and most Earth-like planets outside our own solar system, astronomers at ESO’s La Silla Observatory in Chile have made a remarkable discovery.
Detected using the HARPS instrument on the observatory’s 3.6-metre telescope, they’ve discovered a planet with a similar mass to Earth orbiting a star in the Alpha Centauri star system – our sun’s nearest neighbour in the Milky Way galaxy, ‘just’ 4.3 light years away. Actually a triple-star, Alpha Centauri consists of two stars (or a ‘binary’ star system) similar to our very own Sun, Alpha Centauri A and B, and a third, much fainter, star known as Proxima Centauri. The planet discovery, detailed in the science journal ‘Nature’ yesterday, was a culmination of more than four years’ research using the HARPS instrument, where a “tiny, but real” signal from a planet orbiting Alpha Centauri B was picked up every 3.2 days.
Quite how the team detected the planet itself is truly phenomenal. Bear in mind its location some 25 trillion miles away, the team were able to pick up on a mind-bogglingly small motion of Alpha Centauri B created by the gravitational pull of this then-unknown orbiting planet – a speed of no more than 51 centimetres per second (1.8km/hour) or, as the European Southern Observatory assesses, “about the speed of a baby crawling.”
The planet in question has the smallest mass so far observed from a planet found outside our solar system, coming in at a mass scarily comparable to Earth at about 1.1 times its size. That being said, it’s far from inhabitable, likely so hot at around 2,200 degrees that its rocky surface would be more like molten lava. Though the discovery does hint at something more, with astronomers now hopeful that there are other planets circling the same star, possibly within the habitable zone, or what’s called the ‘Goldilocks Zone’ – a not-too-hot, not-too-cold region of space that could hold intelligent life.
The search continues.