Neutron Stars Weigh 10 Million Tons Per Teaspoon

The incredible density of a neutron star is the result of a massive star's death. When a star many times the mass of our sun runs out of fuel, its core collapses catastrophically in a supernova explosion. The immense gravitational force is so strong that it overcomes the forces that keep atoms apart, crushing protons and electrons together to form a super-dense ball of neutrons. This process packs the mass of a sun into a sphere that is only about 12 miles (20 kilometers) in diameter, roughly the size of a city.

The material that makes up a neutron star is unlike anything on Earth. Its density is comparable to that of an atomic nucleus, which is why even a minuscule amount has an astonishing mass. While the outer crust is thought to be composed of a lattice of iron nuclei, the immense pressure deeper inside likely causes neutrons to 'drip' out of the nuclei, creating a sea of free neutrons. Scientists theorize that at the very center, the pressure might be so extreme that neutrons themselves break down into a bizarre "soup" of their fundamental components, known as quarks.

First predicted in 1933, shortly after the discovery of the neutron, the existence of these strange objects wasn't confirmed until 1967 with the first observation of a pulsar. These rapidly spinning neutron stars act like cosmic lighthouses, sweeping beams of radiation that we can detect from Earth. The study of neutron stars pushes the limits of our understanding of physics, offering a real-world laboratory for exploring the most extreme states of matter in the universe.