A lighthouse flashes for a fraction of a second and goes dark again. The MeerKAT telescope in South Africa catches such flashes in the radio band. During its observations, it picked up 27 new sources that no one had seen before. Neutron stars are the remnants of exploded stars, compressed to the size of a city. Some of them, like a faulty spotlight, emit radio beams not continuously but in short bursts.
For 14 sources, astronomers precisely determined their position on the sky — to within an arcsecond. That's like finding a needle in a haystack, but using a radio map. For 8 of them, they managed to measure the period: the time between successive bursts. The periods turned out to range from 0.78 to 4 seconds. This means the neutron star makes one full rotation in that time, and its beam sweeps across the telescope once per rotation.
Such discoveries help us understand how many neutron stars are in our Galaxy and how they are structured. Perhaps many 'silent' neutron stars are actually just flashing too rarely to be noticed. MeerKAT continues to listen to the sky, and each new pulse is a step toward solving the puzzle.
A neutron star with a period of 1 second rotates faster than helicopter blades, even though its mass is one and a half times that of the Sun.
In Carl Sagan's novel 'Contact', the protagonists detect a radio signal from an extraterrestrial civilization, but in reality, such short bursts are natural beacons, not messages.