Alessandro Ridolfi

A spinning top that whirls so fast it completes 220 rotations in a single second: that's exactly what China's FAST radio telescope has caught. This is the pulsar PSR J1810-0623, a neutron star the size of a city but with more mass than the Sun.

In a close binary system, one star can spend years transferring its material to its companion, like a person gradually giving away everything they own. When the source runs dry, a dense core remains, wrapped in a cloud of its own leftovers.

At night in fog, a searchlight works worse than in daylight: tiny droplets scatter the beam, and distant objects drown in the murky haze. Much the same way, radio waves from pulsars get lost in the interstellar medium when there are many free electrons between us and the star.