Nothing But the Facts About Uranus

Left: true-color image. Center: false-color image, emphasizing the slightly visible cloud bands. The small ring-shaped spots are optical artifacts. Right: Symbol for the planet Uranus.

1) Position in the solar system: 7th planet from the sun

2) Closest distance to the sun: Perihelion: 2.741x10^9 km (1.704x10^9 mi)

3) Furthest distance from the sun: Aphelion: 3.004x10^9 km (1.867x10^9 mi)

4) Minimum Distance to Earth: 2.589x10^9 km (1.609x10^9 mi)

5) Uranian day: 17 hr 14 min 24 sec

6) Uranian year: 84.011 Earth years

7) Axis tilt: 97.77°

8) Orbital Inclination to ecliptic: 0.77°

9) Orbital Eccentricity: 0.046

10) Diameter (equatorial): 51,118 km; (31,770 mi)

11) Mass: 8.68x10^25 kg (1.90x10^26 lb.), approx. 14.5 times that of Earth

12) Gravity: .905 (Earth = 1)

13) Escape Velocity: 21.3 km/s (13.2 mi/s)

14) Temperature: -197°C at 1.0 bar pressure

15) Mean Surface pressure: >1000 bar

16) Atmospheric Composition: 82.5% hydrogen, 15.2% helium, 2.3% methane, with a minor amount of hydrogen deuteride ("heavy" hydrogen) and aerosolized ammonia ice, water ice, ammonia hydrosulfide, and methane ice

17) Number of moons: 27

18) Ringed system? Yes

19) Magnetic Field? Yes

1) Most tilted axis of the planets: Greater than a right angle at nearly 98° (or 82° if the rotation is considered retrograde), Uranus appears to lie almost on its side relative to its orbit.

2) First planet discovered since the ancients: Sir William Herschel observed the planet on March 13, 1781, using a telescope. German astronomer Johann Elert Bode named it after the Greek god of the sky, Ouranos ("Uranos" is the Latin version of the Greek name). Though it is barely visible to the naked eye, the ancients did not recognize that Uranus is a planet because of its dimness and its very slow movement through the sky, a result of its long year.

Uranus Fact Sheet (NASA): http://nssdc.gsfc.nasa.gov/planetary/factsheet/uranusfact.html

Uranus true and false color images taken by the Voyager 2 spacecraft (http://nssdc.gsfc.nasa.gov/image/planetary/uranus/uranus_true_and_false.jpg)

Uranus and moons image taken by the Hubble space telescope (http://solarsystem.nasa.gov/multimedia/gallery/Uranus_Moons-browse.jpg)