The branch of science that studies the universe beyond Earth's atmosphere: Astronomy is the science of the celestial bodies including the sun, the moon, and the planets; the stars and galaxies; and all other objects in the universe.

Astronomy is concerned with the positions, motions, distances, and physical conditions and with the origins and evolution of the celestial bodies which were mentioned previously.

It is divided into such areas as astrophysics, celestial mechanics, and cosmology and it is one of the oldest recorded sciences with observational records from ancient Babylonia, China, Egypt, and Mexico.

Remarkable recent extensions of the powers of astronomy to explore the universe is in the use of rockets, satellites, space stations, and space probes; while the launching of the Hubble Space Telescope into permanent orbit in 1990 enabled the detection of celestial phenomena seven times more distant than by any earth-based telescope.