Photo Credit: Harvard-Smithsonian Center for Astrophysics (CfA)
There’s a new neighbour in the ’hood and it has the astronomy community buzzing. A team called the Pale Red Dot project at Queen Mary University in London has discovered an Earth-like planet orbiting our nearest stellar neighbour. Finding Earth-type planets orbiting other stars is becoming a regular thing, but when it’s orbiting the star nearest to us, that’s very big news. The Alpha Centauri binary star system is usually called our nearest neighbour, but there’s a red dwarf star called Proxima Centauri (loosely orbiting the Alpha Centauri system) that’s just a little closer at 4.25 light years. The newly-discovered planet, Proxima b, is thought to be a rocky planet with a mass similar to Earth or a little more, in an orbit closer than Mercury’s orbit around our Sun. Thanks to the much lower energy output of a red dwarf star, such a close orbit is still within a range that should allow liquid water to exist—what scientists consider the star’s “habitable zone”. So life of a kind we would recognize could possibly survive there, although it wouldn’t have an easy time of it. The planet is probably tidally locked, keeping the same face to its sun all the time—only areas near the night/day dividing line would avoid getting either too much sun for comfort, or an endless cold night. On top of that, Proxima Centauri occasionally sends out burst of x-rays and ultraviolet radiation that might kill off any life trying to gain a foothold there. We also don’t know anything about the planet’s atmosphere. All in all, for any kind of life to exist on Proxima b would be a real long shot (though some scientists consider it a better bet than Mars).
So why all the excitement?
Maybe there’s a lot of astronomy research that’s driven by pure scientific curiosity, but I’d argue that the question we most want answered is, “Are we alone in the universe?” That’s why it was such a thrill when the first planets were confirmed around other stars. Why we get an extra kick when we find planets that are similar to Earth, and especially when they’re in a star’s habitable zone. We can’t help feeling that any of those just might be home to another intelligent race, or at least some form of life that doesn’t come from Mother Earth. But all of those planets discovered so far have been unthinkably far away—there’s no way to reach them within any meaningful timeframe using foreseeable technology (dropping in on the neighbours would take thousands of years in travel time).
Now we see the possibility of a living planet practically next door in galactic terms. Yes, it would still take thousands of years to get there using current technology, but some of the most promising engine tech being developed, like nuclear pulse propulsion or fusion rocket drives might take us there in less than a century. Even more significantly, this new discovery provides the incentive to make that effort.
Humanity is at its most brilliant and daring when faced with a challenge that’s daunting, but still feels achievable. Getting to the Moon was a perfect example—enormous resources were required to make it happen, but first there had to be the will to make it happen. Now, when you combine our most compelling cosmic mystery—the search for other life in the universe—with a target that involves serious obstacles but doesn’t feel completely unachievable, you’ve suddenly got something that can light a fire under our collective backsides.
Yes, we’ll still need to wait for better information about the new planet’s atmosphere, gravity, etc., perhaps from the European Extremely Large Telescope due to enter service in 2024.
But in the meantime, we’ve got a new place to go and an eons-old reason to go there. That makes the discovery of Proxima b a game changer.