Radio pulsar J1574+4703 behaves like a finicky lighthouse. Instead of shining steadily, it turns its radio beam on in short flashes and then falls silent for long stretches. Objects like this are called 'rotating radio transients', or RRATs for short. But this pulsar has a quirk: sometimes it starts working like a normal radio pulsar, sending out signals without interruption.

Scientists listened to J1574+4703 at a frequency of 1250 megahertz using the giant FAST radio telescope — a half-kilometer dish in Guizhou Province, China. It turns out that the star is silent 98% of the time, and only 2% of the time does its radio beam hit Earth. When the pulsar 'switches on', its signal can be of two kinds: normal and unusual. In the unusual mode, the signal changes as if the star briefly loses its rhythm. Moreover, such glitches are more common at the very beginning and end of the active period.

Scientists think the different modes originate at different heights above the star's surface. Where the magnetic field is stronger and denser, radio waves emerge differently. Perhaps this is how normal pulsars gradually turn into silent RRATs, like a person who, with age, joins the conversation less and less.