William Herschel discovers Uranus.

In 1781, astronomer William Herschel made a groundbreaking discovery that would expand our understanding of the solar system—he identified Uranus, the first planet discovered with a telescope. While conducting a sky survey from his home in Bath, England, Herschel initially thought he had found a comet due to its disk-like appearance and movement across the sky. However, further observations and orbital calculations confirmed that it was actually a new planet, making Uranus the first planet discovered in recorded history beyond the five known to ancient astronomers. This discovery challenged existing astronomical models and cemented Herschel’s reputation as a pioneering scientist. King George III even rewarded him for his work, appointing him Court Astronomer. The discovery of Uranus not only doubled the size of the known solar system but also demonstrated the power of telescopic astronomy in uncovering celestial bodies beyond what the naked eye could see.