◆ Uranus Uranus is the 7th planet in the solar system, an ice giant. =============== ===== ====== ==== ==== === ##### ==== === ########### === === ############### === === ################# === === ################# === === ################# === === ############### === === ########### === ==== ##### === ==== ==== ====== ===== =============== Type Planet Magnitude 5.7 Distance 19.60 AU, 163 light-minutes Apparent size 4″ Known as Symbol ♅ Physical Radius 25,362 km, 4 Earths across Mass 15 Earths Density 1.27 g/cm3 Surface gravity 8.9 m/s2, 0.90x Earth's Escape velocity 21.3 km/s Day 17h 14m Year 84.01 Earth years Axial tilt 97.8 degrees Albedo 0.51, reflects 51% of the light hitting it Temperature 76 K, -197 C Moons 28 More information about Uranus Uranus sits right at the edge of what the naked eye can pick up, which is why it was never catalogued as a planet until William Herschel found it with a telescope in 1781. Everything closer in had been known since prehistory. It is also tipped right over onto its side, so instead of spinning like a top it rolls, and each of its poles spends 42 years in continuous sunlight followed by 42 in darkness. In a telescope it is a small blue-green disc and nothing more. It is the only planet with a Greek name rather than a Roman one, and the only one whose naming turned into a long argument. Herschel wanted to call it Georgium Sidus, "George's Star", after the British king who granted him a pension for the discovery. A German astronomer, Johann Bode, proposed Uranus instead in 1782, reasoning that since Saturn was the father of Jupiter in the old stories, the planet beyond Saturn should be Saturn's own father. It took most of a century before everyone was using it. History Discovered 1781, William Herschel, the first planet ever found First visited Voyager 2, 1986, and nothing since Missions Voyager 2 1986 Etymology From Greek Reading Ouranos Literally sky where it is tonight: skymap.sh/Uranus