And talk about heavy: Neutron stars are so dense that a single teaspoon would weigh a billion tons. "If you took Mount Everest and squeezed it into something like a sugar cube, that's the kind of density we're talking about," said NASA's Keith Gendreau.
The small instrument that will study neutron stars, known as NICER (Neutron star Interior Composition Explorer), will be installed on the International Space Station over the next week or so. It was on board the SpaceX spacecraft that arrived at the station Monday.
A neutron star begins its life as a regular star that's about seven to 20 times the mass of our sun, according to NASA. When it runs out of fuel, it collapses under its own weight, crushing its core and triggering a supernova. What remains is an ultra-dense sphere only about 12 miles across, the size of a city, but with up to twice the mass of our sun squeezed inside.
NICER's 56 small telescopes will observe neutron stars, enabling scientists to determine their size and composition.
The mission will also study pulsars, which are neutron stars that can spin hundreds of times a second, emitting pulses of radiation as they do. Pulsars are like cosmic lighthouses, NASA said, which appear to wink on and off as their spin sweeps beams of radiation past us.