Rings of Uranus to the numbering of the occultation events in one paper. Uranus's ring system was the second to be discovered in the Solar System, after that of Saturn. The rings were directly imaged when the "Voyager 2" spacecraft flew through the Uranian system in 1986. Two more faint rings were revealed, bringing the total to eleven. The Hubble Space Telescope detected an additional pair of previously unseen rings in 2003–2005, bringing the total number known to 13. The discovery of these outer rings doubled the known radius of the ring system. Hubble also imaged two small satellites for the first time,
IAU definition of planet IAU definition of planet The International Astronomical Union (IAU) defined in August 2006 that, in the Solar System, a planet is a celestial body which: Among other things, this definition caused Pluto to no longer be a planet, a change from how it had been widely considered until that point. A non-satellite body fulfilling only the first two of these criteria (such as Pluto) is classified as a "dwarf planet". According to the IAU, "planets and dwarf planets are two distinct classes of objects". A non-satellite body fulfilling only the first criterion is termed a "small Solar System body" (SSSB).