A unit of distance equaling one bilionth of a meter. 1 nm = 0.000,000,001 m.
NASA
National Aeronautics and Space Administration
neutrino
A neutral, massless atomic particle that travels at the speed of light.
neutron
An atomic particle with no charge and about the mass of a proton.
neutron star
A small, highly dense star composed almost entirely of tightly packed
neutrons. Radius about 10 kilometers.
nova
From the Latin, meaning "new", a sudden brightening of a star making
it appear as a new star in the sky. Believed to be associated with
eruptions on white dwarfs in binary systems.
nuclear bulge
The spehrical cloud of stars that lies at the cneter of spiral galaxies.