中子星
Neutron stars have overall densities of to ( to times the density of the Sun), which is comparable to the approximate density of an atomic nucleus of . The neutron star's density varies from about in the crust—increasing with depth—to about or (denser than an atomic nucleus) deeper inside. A neutron star is so dense that one teaspoon (5 milliliters) of its material would have a mass over , about 900 times the mass of the Great Pyramid of Giza. In the enormous gravitational field of a neutron star, that teaspoon of material would weigh , which is 15 times what the Moon would weigh if it were placed on the surface of the Earth. The entire mass of the Earth at neutron star density would fit into a sphere of 305 m in diameter (the size of the Arecibo Telescope). The pressure increases from to from the inner crust to the center.