Juno, minor-planet designation 3 Juno in the Minor Planet Center catalogue system, was the third asteroid to be discovered and is the 11th-largest asteroid in the asteroid belt, and 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 German astronomer Karl L. Harding.