An enigmatic radio signal from the direction of Proxima Centauri, the Sun’s nearest stellar neighbor, has set the internet ablaze with rumor and speculation. It could turn out to be the real deal — a calling card from another civilization. More likely, it’s much ado about nothing.

The discovery was leaked to the British newspaper The Guardian, which reported the story December 18. Researchers subsequently granted interviews to Scientific American and National Geographic. Since then, however, the discovery team has remained tight-lipped about the signal.

But the information revealed to date is intriguing. READ MORE

Ever since 1992, when astronomers first discovered two rocky planets orbiting a pulsar in the constellation Virgo, humans have known that other worlds exist beyond our solar system. Today, thanks to the efforts of astronomers and ambitious missions like the now-retired Kepler, we know of more than 4,000 confirmed exoplanets.

But if we can see exoplanets orbiting distant stars, that means extraterrestrial observers should be able to see Earth orbiting the Sun. Our tiny blue marble even could be on an alien astronomer’s list of rocky exoplanets capable of harboring life.

That’s a speculative scenario, of course, but it’s one astronomers still take seriously. In multiple papers over the years, they’ve identified which exoplanets would be able to spot Earth. And now, with updated information from the European Space Agency’s expansive Gaia catalog of nearby stars, two researchers have provided us with perhaps the best list yet of which alien worlds could have their eyes on us.