What is the study of stars, planets and galaxies called?

The study of stars, planets, and galaxies is called astronomy. It is a natural science that examines objects and phenomena beyond Earth's atmosphere, including moons, comets, asteroids, nebulae, black holes, and the large-scale structure of the universe.

Astronomy is one of humanity's oldest sciences. Ancient Babylonian, Egyptian, Chinese, Greek, Indian, Maya, and other cultures observed the sky to create calendars, navigate, plan agriculture, and understand recurring celestial events. The field changed dramatically after the telescope became practical in the early 17th century, allowing observers to study objects invisible to the naked eye.

Modern astronomy overlaps with astrophysics, which uses physics and chemistry to explain how celestial objects form, behave, and evolve. It should not be confused with astrology: astronomy is evidence-based science, whereas astrology interprets celestial positions as influences on human affairs. Major branches include planetary, stellar, galactic, and observational astronomy.