Planet planet Venus, that probably dates as early as the second millennium BC. The MUL.APIN is a pair of cuneiform tablets dating from the 7th century BC that lays out the motions of the Sun, Moon, and planets over the course of the year. The Babylonian astrologers also laid the foundations of what would eventually become Western astrology. The "Enuma anu enlil", written during the Neo-Assyrian period in the 7th century BC, comprises a list of omens and their relationships with various celestial phenomena including the motions of the planets. Venus, Mercury, and the outer planets Mars, Jupiter, and Saturn were
Planet the Drake equation, which estimates the number of intelligent, communicating civilizations that exist in the Milky Way. There are exoplanets that are much closer to their parent star than any planet in the Solar System is to the Sun, and there are also exoplanets that are much farther from their star. Mercury, the closest planet to the Sun at 0.4 AU, takes 88 days for an orbit, but the shortest known orbits for exoplanets take only a few hours, e.g. Kepler-70b. The Kepler-11 system has five of its planets in shorter orbits than Mercury's, all of them much more massive