Last week, researchers from The Pale Red Dot project announced that they had found evidence of a potentially earth-like exoplanet orbiting the closest star to our sun, Proxima Centauri, part of the Alpha Centauri triple star system which lies just four (relatively) short light-years away from our own Sol system.
The researchers explain in their findings – published in the journal Nature – that the planet, named “Proxima b”, was discovered by measuring the minute gravitational “wobbles” of Proxima Centauri caused by the gravitational pull of the orbiting planet using a process called Doppler spectroscopy; thus, while its existence and physical parameters can only be inferred, researchers can combine this information with other astronomical data to make educated guesses about the nature of Proxima b.
So what do we know about it? Well researchers say it’s definitely terrestrial (meaning that it has a rocky surface), and that it is approximately 1.3 times Earth’s mass. It orbits its parent star every 11.2 days at a distance of just 7.5 million kilometers (for comparison, one astronomical unit, defined as the distance from the sun to earth, is approximately 150 million kilometers), and at that distance is almost certainly tidally locked, meaning one side always faces the sun while the other remains in perpetual darkness. Despite these conditions however, researchers say that the planet is potentially in the habitable zone (defined as the area around a star where liquid water can exist on the planet’s surface), as Proxima Centauri is a red dwarf and thus considerably smaller and less energetic than our own sun.
The question of whether or not alien life (most likely microbial in nature) exists on Proxima b is difficult to determine, especially without the ability to measure the composition of its atmosphere, if one exists. Upcoming space projects like the James Webb Space Telescope (NASA’s replacement for Hubble) could potentially give researchers the ability to directly image the planet and to measure the refracted light of the star coming around the planet to determine more about its composition – and if it does turn out to have an atmosphere, we may perhaps even be able to detect the tell-tale signs of liquid water (and thus, potentially life) on its surface.
The discovery has sent a wave of excitement and speculation through the scientific world, especially since the planet is by far the closest ever discovered outside our own solar system, and thus a could potentially one day be directly explored (and even colonized, if conditions are right) by humanity – after all, if we’re going to go out and explore the galaxy one day, one would think that our first stop would be our closest stellar neighbor. However, getting there is still rather tricky, and by current conventional means would take hundreds of thousands of years – our furthest spacecraft, Voyager 1, has traveled “only” 20 billion kilometers (roughly 0.0005% of the total distance to Proxima Centauri) in 40 years.
Despite this, scientists working on the project expressed hope that future research would prove fruitful. “Many exoplanets have been found and many more will be found, but searching for the closest potential Earth-analogue and succeeding has been the experience of a lifetime for all of us,” said Dr Guillem Anglada-Escudé, lead author of the report and a senior researcher at Queen Mary University in London. “Many people’s stories and efforts have converged on this discovery. The result is also a tribute to all of them.”