Pulsar Mystery: How Hot Spots Revealed the Star's Size
A neutron star is a sphere the size of a city but with the mass of the Sun. A single teaspoon of its material would weigh as much as a mountain. The star PSR J0030+0451 spins hundreds of times per second and emits narrow beams of X-rays. When a beam sweeps past Earth, we see a brief flash, like the light from a lighthouse.