German astronomer, Johann Galle discovered Uranus (below):
Image sourced from http://www.crystalinks.com/uranus.jpg\
Neptune (below) discovered by Johann Galle and a few mates.
Image sourced from http://amazing-space.stsci.edu/resources/fastfacts/graphics/neptune.jpg
Pluto (below) discovered by American astronomer, Percival Lowell.
Image sourced from http://www.elsaelsa.com/wp-content/uploads/2011/01/pluto.jpg
Check out New technologies and De-discoveries for even more advancements in the telescope!