Vivek Venkatraman Krishnan

Imagine two neutron stars, compressed to the size of a metropolis yet weighing one and a half Suns each. They whirl in an unrestrained gravitational dance, drawing together and flying apart every 4.4 hours. At periastron — the point of closest approach — only a couple of light-seconds separate them, and their speed reaches three and a half million kilometers per hour.

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.