Ancient civilizations, such as the Babylonians and Egyptians, made systematic observations of the stars for religious and agricultural purposes.

The ancient Greeks developed the first scientific models of the cosmos, culminating in Ptolemy's geocentric (Earth-centered) model.

The Copernican Revolution of the 16th century marked the beginning of modern astronomy, with Copernicus proposing a heliocentric (Sun-centered) model.

Johannes Kepler calculated that planets move in elliptical, not circular, orbits.

Galileo Galilei's use of the telescope in the early 17th century provided the first direct observational evidence for the Copernican model.

Isaac Newton's law of universal gravitation provided a physical explanation for the motions of the planets.

In the 20th century, Edwin Hubble's observations proved that the universe is expanding and that there are other galaxies beyond our own.

The theory of the Big Bang emerged as the dominant cosmological model for the origin of the universe.

The development of radio telescopes, space telescopes (like the Hubble), and other instruments has allowed astronomers to study the universe in unprecedented detail.

Modern astronomy continues to explore fundamental questions about dark matter, dark energy, and the existence of extraterrestrial life.