Galileo's major contribution to astronomy was his use of the telescope to make groundbreaking observations that revolutionized our understanding of the universe. Here are some key points to consider:
1. **Observations of the Moon:** Galileo discovered that the Moon's surface was not smooth but had mountains, valleys, and craters. This challenged the belief at the time that celestial bodies were perfect and unchanging.
2. **Discoveries of Jupiter's Moons:** Galileo observed four large moons orbiting around Jupiter. This discovery supported the idea that not all celestial bodies orbited around the Earth, as was commonly believed in the geocentric model.
3. **Phases of Venus:** By observing Venus through his telescope, Galileo was able to show that Venus goes through phases similar to the Moon, providing evidence for the heliocentric model proposed by Copernicus, where the planets revolve around the Sun.
4. **Sunspots:** Galileo's observations of sunspots demonstrated that the Sun was not a perfect, unblemished sphere but had imperfections on its surface, further challenging the geocentric view of the universe.
In summary, Galileo's use of the telescope and his observations of celestial bodies played a crucial role in challenging traditional beliefs about the nature of the universe and laying the foundation for modern astronomy.
