S. Guillot

In a dark corner of the Milky Way, a natural metronome is at work. Every 8196 seconds, about 2 hours and 16 minutes, X-ray light flares on the surface of a neutron star. The star EP J171159.4-333253 pulls gas from a neighboring star, and this gas, falling inward, accumulates on its surface.

After a supernova explosion, a neutron star neutron star remains: a city-sized ball of unimaginably dense matter, spinning hundreds of times per second. Any tiny bump on its surface would make it wobble like an off-balance spinning top, humming faintly through the fabric of space.

A neutron star is a city the size of Manhattan, compressed to such a density that a teaspoon of its material weighs as much as Mount Everest. To understand what it's made of inside, scientists measure its radius. But there's a catch: many measurements suffer from systematic errors, like trying to measure the height of someone who keeps fidgeting and bending over.