3 Juno or Juno is an asteroid and basically considered as a planet. It is large main-belt asteroid. It contains approximately 1% of the total mass of the asteroid belt. It is considered as the second enormous S-type asteroid and third asteroid to be discovered.

It was discovered by Karl Ludwig Harding, a German astronomer. It was discovered at Schroter’s observatory on September 1, 1804. Johann Hieronymus Schroter, a German astronomer estimated its diameter of around 2290 km in 1811.