Astronomy, a natural science, is the study of celestial objects (such as stars, galaxies, planets, moons, asteroids, comets and nebulae) and processes (such as supernovae explosions, gamma ray bursts, and cosmic microwave background radiation), the physics, chemistry, and evolution of such objects and processes, and more generally all phenomena that originate outside the atmosphere of Earth. A related but distinct subject, physical cosmology, is concerned with studying the Universe as a whole. Astronomy is one of the oldest sciences. The early civilizations in recorded history, such as the Babylonians, Greeks, Indians, Egyptians, Nubians, Iranians, Chinese, and Maya performed methodical observations of the night sky. However, the invention of the telescope was required before astronomy was able to develop into a modern science.
astronomy n. Astrology.
astronomy n. The science which treats of the celestial bodies, of their magnitudes, motions, distances, periods of revolution, eclipses, constitution, physical condition, and of the causes of their various phenomena.
astronomy n. A treatise on, or text-book of, the science.
astronomy n. study of celestial bodies (stars, planets, etc.)