Joe Palca | NPR

Scientists say a brief burst of radio activity has been detected at the Arecibo radio telescope in Puerto Rico. This new report resembles previous activity detected in Australia, which has scientist debating possible causes, including solar flares, blitzars, or something even more mysterious.
Astronomers have a mystery on their hands. Two large radio telescopes, on opposite sides of the planet, have detected very brief, very powerful bursts of radio waves.
Right now, astronomers have no idea what's causing these bursts or where they're coming from. And nothing has been ruled out at the moment — not even the kind of outrageous claims you'd expect to see in tabloid headlines.
Australian Recordings Inspire Curiosity And Doubt
The Parkes Observatory, in New South Wales, Australia, first detected the brief, intense bursts of radio waves in 2007.
The first report of these “fast radio bursts” appeared in 2007. Duncan Lorimer and his colleagues had found the signal buried in recordings made at the Parkes radio telescope in Australia.
Lorimer argued at the time that the source of the burst came from way beyond our galaxy. But then the same telescope recorded more bursts that were similar, but clearly coming from something much closer by.
“They cast a lot of doubt on the original detection that we made,” Lorimer says; something nearby would probably have a much more pedestrian explanation.
Other astronomers began to suspect Lorimer's extra-galactic detection was a fluke — but that changed last year, when a significant paper in Science announced the discovery of four more bursts.
That paper convinced most astronomers that something real, far away and still very mysterious was happening.
But there was one lingering doubt. All of the detections were made by one radio telescope, the Parkes telescope. Some astronomers wondered if the bursts might not be an astronomical event at all, but some problem with the electronics in the telescope.
But now, Lorimer says, “It's clearly not.”
In Puerto Rico, Fresh Reports Renew Speculation
There's a report of a burst detected at the Arecibo radio telescope in Puerto Rico. Lorimer says several more reports of detections will soon be showing up in the scientific literature.