Astronomers searching for signs of life beyond Earth have spotted something strange. An as-yet unexplained radio signal appears to be coming from the direction of the star closest to the sun—a small red star roughly 4.2 light-years away called Proxima Centauri. Adding to the excitement, at least two planets orbit this star, one of which might be temperate and rocky like Earth.

“It’s pretty expected that every now and then you’ll see something weird, but this is interesting because it’s something that’s weird that we’re having to think about the next steps,” says Sofia Sheikh, a graduate student at Pennsylvania State University and the Breakthrough team member leading the signal analysis.

Though Sheikh and others strongly suspect that the