Mercury wasn’t “discovered” in a specific year by a single person; it has been known since ancient times and was observed by many early civilizations long before modern astronomy existed. One of the earliest written records of Mercury comes from the Sumerians around 3000 BC, and it was also tracked by Babylonians, Egyptians, and Greeks, who associated it with their messenger gods (Nabu, Hermes, and later the Roman Mercury).

In a more modern sense, astronomers recognized Mercury as a planet in the heliocentric solar system when Nicolaus Copernicus published his Sun‑centered model in 1543, which placed both Earth and Mercury in orbit around the Sun. This view was later supported by early telescopic observations in the 17th century.