Juno was discovered on 1 September 1804 by Karl Harding at Lilienthal, the third asteroid found. It is a stony body of moderate size in the main belt and, like Pallas, was briefly counted a planet before the asteroid category was established. The name is that of the Roman Juno, the Greek Hera, queen of the gods and wife of Jupiter, whose cult title Juno Pronuba attached her to marriage and whose mythology is dominated by her husband's infidelities and her responses to them. Modern astrological practice, again dating from the 1970s asteroid literature, reads Juno for marriage and committed partnership, for the terms on which a person bonds, and for the shadow side of that: jealousy, betrayal and the negotiation of power within a relationship. As with the other asteroids, the meaning follows from the mythological name given by the discoverer and is a modern construction.
Juno's status as the third asteroid discovered, after Ceres and Pallas, places its find within a short, intense burst of early nineteenth-century asteroid-hunting, all four of the earliest asteroids, Ceres, Pallas, Juno and Vesta, were located within eight years of one another between 1801 and 1807 before a long gap of decades before the next discoveries, a pattern astronomers of the period took as suggestive of a systematic search region between Mars and Jupiter rather than scattered chance finds.