GW170817

Gamma-ray bursts are flashes of gamma rays from collapsing massive stars and merging neutron stars. Learn how they work, how astronomers catch them, and why the brightest one on record, GRB 221009A, still puzzles researchers.

Neutron stars pack more mass than the Sun into a sphere about the size of a city. This guide covers how they form, what lies inside them, how heavy they can get, and why pulsars, magnetars and neutron star mergers matter to physics.