A Teaspoon of Neutron Star Material Would Weigh as Much as Mount Everest

Neutron stars are formed when massive stars explode as supernovae and their cores collapse under their own gravity. The resulting object is so dense that it crushes matter to nuclear density—approximately 10^14 times denser than water. A neutron star typically measures only about 20 kilometers (12.5 miles) across yet contains as much mass as our entire Sun. The density is so extreme that a normal-sized matchbox of neutron star material would weigh approximately 3 billion tonnes, equivalent to a 0.5 cubic-kilometer chunk of Earth. To contextualize the teaspoon measurement: at 4.929 milliliters, a teaspoon of neutron star material would have a mass of 5.5 × 10^12 kilograms (5,500,000,000 metric tons). If all of Earth's mass were compressed to neutron star density, it would fit into a sphere only 305 meters in diameter—roughly the size of the Arecibo radio telescope. The extreme density creates an incredibly strong gravitational field and magnetic field on a neutron star's surface. Some neutron stars, called magnetars, have magnetic fields a thousand times stronger than typical neutron stars.