Mercury, the planet, was not discovered by any single person because it has been known since ancient times. It is one of the five classical planets visible to the naked eye and was observed by many early civilizations, including the Sumerians around 3000 BC

. The Greeks initially thought the morning and evening appearances of Mercury were two separate objects, naming them Apollo and Hermes, but by about the 4th century BC, they realized these were the same planet

. The planet was first observed through telescopes in the early 17th century by astronomers Galileo Galilei and Thomas Harriot, marking the beginning of telescopic study of Mercury

. However, the knowledge of Mercury as a planet predates telescopic observations by millennia. In summary, Mercury was known to ancient civilizations long before recorded history, and no single individual is credited with its discovery. The first telescopic observations were made by Galileo Galilei and Thomas Harriot in the 1600s