neutron-stars

Roughly 44% of Sun-like stars have a companion, and the share climbs past 80% for the most massive stars. Binary stars let astronomers weigh stars, produce Type Ia supernovae and millisecond pulsars, and generate the gravitational waves LIGO detects.

Atoms are almost entirely empty space. If you compressed all of humanity to nuclear density, the result would be about the size of a sugar cube. Here's the quantum physics behind why that doesn't work in ordinary matter, and where stars do it anyway.

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.

Stars don't burn out quietly. Depending on their mass, they end their lives as cooling embers, supernova explosions, neutron stars, or black holes. Here's what actually happens.

Einstein predicted them in 1916. We detected them for the first time in 2015. Gravitational waves let us "hear" cosmic events that produce no light. Here's how they work and what they reveal.