Who
Galileo Galilei was one of the astronomers to discover some of the planets that were in space. He found out that the moon has craters, He discovered Venus. In 1610, he looked through his telescope and saw Venus. He also discovered Jupiter and Saturn. He also discovered five of Jupiter's moons. Johann Gottfried Galle discovered Neptune. William Herschel Discovered Uranus. It wasn't all Galileo Galilei who discovered every planet in space. The reason why Johann Gottfried Galle and William Herschel discovered them many years after Galileo passed away, was because a more powerful telescope was invented to let people see the outer planets that you can not see with the naked eye.