What An Earth-Like World Around Proxima Centauri Would (And Wouldn’t) Mean
“Whether this planet exists or not — and it’s important to be skeptical, as there was a planet reported around Alpha Centauri B a few years ago that went away with more data — it’s important to remember that ‘Earth-like’ is a far cry from being anything at all like the actual Earth. By these criteria, Venus or Mars would be ‘Earth-like’ too, but you wouldn’t stake your hopes of becoming an interstellar species on either of those. As great as finding a new, rocky world in the potentially habitable zone around the nearest star to the Sun would be, it’s a long way from our ultimate dream of an Earth 2.0.”
Later tonight, the European Southern Observatory is expected to make an announcement, and the smart money is on the discovery of an Earth-like planet orbiting Proxima Centauri, the nearest star to our Sun. As incredibly exciting as this news is, however, it’s important to keep in mind that “Earth-like,” to an astronomer, means something very different than what we think of as “actually like Earth.” The only information we can glean from our present observations is the planet’s mass, size and orbit around a star. This is enough to tell us some of its properties, including a few ways (like tidal locking) that are quite different from Earth, but questions about its atmosphere, surface temperature, magnetic field and much more remain unanswered.