Neutron stars are the superdense "corpses" of massive stars that have exploded as supernovae. With all their mass packed into a sphere sometimes as small as the size of a city, their protons and electrons are crushed together into neutrons. A thimbleful of neutron-star material could weigh more than 500 million tons. Astronomers using the Robert C. Byrd Green Bank Telescope (GBT) in West Virginia have discovered the most massive neutron star yet found -- a discovery with wide-ranging implications across several fields of physics and astrophysics.