This radio signal, now seen on three separate occasions, is an enigma. It could be generated by a previously unknown astronomical phenomenon. Or it could be something much more mundane, maybe an artefact of the telescope itself.
But it also happens to be the best candidate yet for a contact by intelligent aliens in the nearly six-year history of the SETI@home project, which uses programs running as screensavers on millions of personal computers worldwide to sift through signals picked up by the Arecibo telescope.
The signal's frequency is one of the main frequencies at which hydrogen, the most common element in the universe, readily absorbs and emits energy; if you were an alien trying to communicate something to the universe, you might use this part of the radio spectrum.
There are other oddities.
However, Seth Shostak of the SETI Institute sets the record straight for Space.com. The hopes expressed in the New Scientist article are all hyperbole.
The statistics of noise make it fairly likely that at least one of the candidates observed . . . would reappear, even if all these signals were simply due to receiver fluctuations.
As yet, there's no good reason to believe we're about to patch through a call to another civilization.
He reassures us that when the SETI project has some real evidence, we'll know about it.
What if, just like us, the aliens aren't transmitting, but just sitting at home quietly, listening?