Galileo Galilei is one of the most revered scientists of all time. What descoveries did he make with his simple telescope?

Galileo made many discoveries with his telescope. He observed the moon and contrrary to popular belief at that time, found its surface to be rough irregular and covered in depressions. Also, he observed that the moon was not perfectly spherical. He observed the planet Jupiter and discovered its four moons, that weakened the hold of the Ptolemic model. He observed the phases of Venus that looked similar to those of the Moon. This could not be explained in the Ptolemaic model but made sense considering the Sun-centered Copernican model. He observed dark spots on the Sun, and used this observation to infer that the Sun was rotating. His observations led him to conclude that the earth was not stationary, and orbited the Sun.