A neutron star is the result of a supernova explosion when a star collapses into a dense mass of neutrons. A teaspoon of material of a neutron star weighs about 10,000 tonnes! That should be easier to imagine, considering that neutron stars generally have the mass of an ordinary star but packed into a much smaller area. They are over 150 times hotter than the sun and spin quite rapidly- some neutron stars can rotate 1000 times per second.
