Stories about potentially Earth-like planets orbiting far away stars have been making the headlines for years. With the Kepler spacecraft monitoring the stars, searching for telltale dips in brightness that indicate the presence of a planet, and a host of telescopes adding their capabilities to the mix, discoveries have been coming in at an amazing pace. But with each new potential Earth 2.0, the excitement is a little less, especially considering that even the closest discovery is so far away that each represents little more than a curiosity – until now.
Using two instruments mounted on telescopes in Chile – the Ultraviolet and Visual Echelle Spectrograph (UVES) and the High Accuracy Radial velocity Planet Searcher (HARPS) – astronomers detected a slight wobble in the red dwarf star, Proxima Centauri, which indicates the presence of a planet. After focusing HARPS on the star for months in early 2016, and combining it with data from earlier HARPS and UVES observations, these astronomers are declaring they’ve found a roughly Earth-sized planet orbiting Proxima Centauri in the habitable zone. What makes this so special is that Proxima Centauri is our closest stellar neighbor – only 4.2 light years from us.
What is This Planet Like?
The new planet, labeled Proxima b, is about 1.3 times more massive than the Earth. Surface gravity could be in the range of Earth’s, depending on the density, and thus size, of the planet. Proxima Centauri is a very small, dim, red star which is much less bright than our Sun – .17% to be exact – and thus the planet can be much closer and still be in the habitable zone. It is estimated that Proxima b is only 4.7 million miles from its star (compared to Earth’s 93 million miles), and completes an orbit once every 11 days.
Could There Be Life on Proxima b?
Proxima Centauri is a very active star as far as solar flares are concerned. Given how close Proxima b is to the star, it is safe to say it gets blasted by radiation. What is not known about the planet is whether it has a magnetic field strong enough to protect it. Even if it does, much earlier in the star’s life it was much brighter and hotter than it is now. Just like Mercury, the closest planet to our Sun, has no atmosphere because it was blasted away by the planet’s proximity, it is possible Proxima b could have at one time been in a similar situation.
Additionally, even if there is an atmosphere, there’s nothing that indicates whether it is remotely Earth-like. It is far too early to even speculate about life. The interesting thing about this planet is that it is so close to us that we can get visual images of it with a large enough and sufficiently advanced telescope. Such images could shed light, literally, on the planet and its atmosphere.
Could Humans Travel There?
Considering humans haven’t yet traveled to the nearest planet, getting 4.2 light years to Proxima Centauri is fairly far outside of our foreseeable capabilities. As I wrote a couple of months ago, there is an ambitious project backed by Stephen Hawking, Mark Zuckerberg and entrepreneur Yuri Milner called Breakthrough Starshot that proposes sending a bunch of tiny solar sails through space to our neighboring stars. Those little space ships would be accelerated by a massive laser to 20% of the speed of light, allowing them to traverse the void between the stars in as little as 25 years. First, the technology that would allow humans to live in space for that long has not been developed. Second, it would be far longer than 25 years using existing or planned thrusters. It would be a monumental task, but one that is at least within the realm of feasibility, which allows us to dream.