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Neutron Stars

Artist's impression of a neutron star
Credit: Casey Reed/Penn State University

A neutron star is the incredibly compact core that remains after a supernova event.

When a high-mass star comes to the end of its lifetime, its outer layers collapse onto the core, compressing material to the point where the atoms are smashed apart, leaving only neutrons - sub-atomic particles with no electric charge.

The outer layers are then ejected in a super-massive explosion, leaving a rapidly spinning neutron star behind. Some neutron stars have been found to rotate at several hundred times a second.

A neutron star can weigh the same as one or two Suns and yet will only be about 20 km across. For comparison, a matchbox of neutron star material would weigh the same as the country of Wales. A house of it would weigh the same as the Moon.