But in at least one sense, the news is different from similar findings made in recent years. The star, known as Proxima Centauri, is too faint to see with the naked eye, but it is the closest star to Earth. If human beings ever leave the bounds of their star and head toward another, they will probably go to Proxima. There might be nothing there, not a colony of microbes nor a community of advanced beings. But as far as listening goes, in the effort to search the cosmos for a sign of something both familiar and extraordinary, Proxima might be a sensible target.
Proxima—Latin for “nearest”—is located just 4.2 light-years away, in a triple-star system known as Alpha Centauri. Since its discovery in 1915, Proxima has regularly appeared in science-fiction tales of interstellar arks and alien empires. When the field of SETI—the “search for extraterrestrial intelligence”—began in earnest in the 1960s, Proxima was one of the first places researchers considered. When your search spans the observable universe, proximity certainly matters.
Unlike its two sibling stars in Alpha Centauri, Proxima is not like the sun. It is smaller, cooler, and dimmer. But it does have at least two planets. One of them, known as Proxima c, orbits farther from the star, like a miniature Neptune. The other, Proxima b, is closer in—so close that its year lasts only 11 days. Proxima b is rocky, about the same size as Earth, and within the star’s habitable zone, a region where temperatures might allow water to flow on its surface.
We don’t know what Proxima b looks like, and the astronomers studying BLC1 aren’t suggesting that the beam originated there. Contrary to some early sci-fi tales, Proxima b would make a terrible second home for us, and might not be an easy place for any kind of life to take hold, despite its potentially balmy climate. Stars like Proxima Centauri are known to unleash torrents of radiation, enough to strip a nearby planet of its atmosphere over many years.
The public’s enthusiasm about BLC1 might have been premature, but if humankind ever does hear from an advanced alien civilization, the call could come from nearby. It might sound presumptuous to suggest that, out of the hundreds of billions of stars in the Milky Way, we could discover intelligent life on the next one over. And, well, it is pretty presumptuous. But it’s not impossible. “It’s probably slightly more likely that we would find intelligent life on Proxima than anywhere else,” Sheikh said. “Assume that aliens are everywhere, [that] every star has a humanlike civilization, then they might all be saying hi. But the one we’re gonna see first is the closest, because that will be the one that we’re able to detect.”