Pre-telescopic research thumb|left|Model in the Almagest of the longitudinal motion of Jupiter (☉) relative to Earth (🜨)|230x230px Observation of Jupiter dates back to at least the Babylonian astronomers of the 7th or 8th century BC. The ancient Chinese knew Jupiter as the "Suì Star" ( ) and established their cycle of twelve earthly branches based on the approximate number of years it takes Jupiter to revolve around the Sun; the Chinese language still uses its name (simplified as ) when referring to years of age. By the 4th century BC, these observations had developed into the Chinese zodiac, and each year became associated with a Tai Sui star and god controlling the region of the heavens opposite Jupiter's position in the night sky. These beliefs survive in some Taoist religious practices and in the East Asian zodiac's twelve animals. The Chinese historian Xi Zezong has claimed that Gan De, an ancient Chinese astronomer, reported a small star "in alliance" with the planet, which may indicate a sighting of one of Jupiter's moons with the unaided eye. If true, this would predate Galileo's discovery by nearly two millennia.
pre-telescopic research thumb|left|model in the almagest of the longitudinal motion of jupiter (☉) relative to earth (🜨)|230x230px observation of jupiter dates back to at least the babylonian astronomers of the 7th or 8th century bc the ancient chinese knew jupiter as the "suì star" ( ) and established their cycle of twelve earthly branches based on the approximate number of years it takes jupiter to revolve around the sun; the chinese language still uses its name (simplified as ) when referring to years of age by the 4th century bc these observations had developed into the chinese zodiac and each year became associated with a tai sui star and god controlling the region of the heavens opposite jupiter's position in the night sky these beliefs survive in some taoist religious practices and in the east asian zodiac's twelve animals the chinese historian xi zezong has claimed that gan de an ancient chinese astronomer reported a small star "in alliance" with the planet which may indicate a sighting of one of jupiter's moons with the unaided eye if true this would predate galileo's discovery by nearly two millennia