Galileo Galilei 1564–1642
Italian Astronomer
Galileo Galilei (gal uh LAY oh gal uh LAY) was an Italian astronomer who loved to ask questions about the world. In 1609, he heard about a new invention, the telescope. It allowed people to see things from far away. Galileo decided to make a telescope of his own. Through it, he saw things no one had ever seen before. He looked at the moon's craters. He also watched four of Jupiter's moons slowly orbit that planet.
Galileo realized that Earth was not the center of the universe, as most people had thought. Instead, he agreed with an earlier scientist named Copernicus (koh PUR nuh kuhs) that Earth revolved around the sun. Galileo's findings challenged what most people thought about the universe. Today, however, we know that Galileo was right about Earth's relation to the sun.
Critical Thinking
What problem did Galileo solve by building his own telescope?