Juno, minor-planet designation 3 Juno in the Minor Planet Center catalogue system, was the third asteroid to be discovered and is one of the larger main-belt asteroids, being one of the two largest stony (S-type) asteroids, along with 15 Eunomia. It is estimated to contain 1% of the total mass of the asteroid belt. Juno was discovered on September 1, 1804 by Karl L. Harding. It is an S-type asteroid.
3 Juno is named after the mythological Juno, the highest Roman goddess.