Astronomy: The scientific study
of the Galaxies, Stars, Nebulae, Solar Systems and the
Universe. It deals with a celestial object's
relationship to the Earth, size, position, composition, motion,
evolution and energy. Astronomers use telescopes, satellites,
computers, space stations and observatories to study the universe.
Extragalactic Astronomy: The
study of Galaxies outside of the Milky way.