Galileo Galilei made several groundbreaking contributions to astronomy that fundamentally changed our understanding of the universe. His key contributions include:
- Improvement of the Telescope – Galileo improved the design of the telescope, allowing for much greater magnification than previously possible. This enabled him to make detailed astronomical observations.
- Discovery of Jupiter’s Moons – In 1610, he discovered four large moons orbiting Jupiter (now known as the Galilean moons: Io, Europa, Ganymede, and Callisto). This provided strong evidence against the geocentric (Earth-centered) model of the universe.
- Observations of the Moon – Galileo observed that the Moon’s surface was rough and covered in craters and mountains, contradicting the belief that celestial bodies were perfect and smooth.
- Phases of Venus – He observed that Venus goes through a full set of phases, similar to the Moon. This was strong evidence in favor of the heliocentric (Sun-centered) model proposed by Copernicus.
- Milky Way Composition – Galileo discovered that the Milky Way is composed of countless individual stars, challenging the Aristotelian view of a uniform celestial sphere.
- Sunspots – He observed dark spots on the Sun’s surface, proving that the Sun was not a perfect, unchanging celestial body as previously believed.
- Support for Heliocentrism – Through his observations, Galileo provided significant evidence for the Copernican heliocentric model, though this led to conflicts with the Catholic Church.
His contributions laid the foundation for modern observational astronomy and helped shift scientific thought away from the geocentric model toward a more accurate understanding of the solar system.