astronomy

astronomy, branch of science that studies the motions and natures of celestial bodies, such as planets, stars, and galaxies; more generally, the study of matter and energy in the universe at large.

Sections in this article:

• Introduction
• Modern Techniques, Discoveries, and Theories
• Astrophysical Discoveries
• Galileo's Telescope
• Brahe and Kepler
• The Copernican Revolution
• The Alexandrian School and the Ptolemaic System
• Greek Innovations
• Ancient Astronomy
• Bibliography

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2025, Columbia University Press. All rights reserved.

See more Encyclopedia articles on: Astronomy: General