Discovered as a planet by William Hershel in 1781, Uranus can be seen with the naked eye, but was always thought to be a star due to its very long orbital period. This discovery helped make Hershel famous and provided a annual stipend of £200 from King George III.

The composition of Uranus is different from Jupiter and Saturn. While the two large planets are gas giants mostly made of hydrogen and helium, Uranus and Neptune are ice giants with a mantle of compressed water, ammonia and methane ice with an atmosphere of hydrogen.
While we can view Uranus from Henize, it is a boring blue-green ball in the eyepiece.

Uranus has an extreme axial tilt. This causes wind speeds on Uranus to reach 900 km/h during the solstice as energy flows from the hemisphere facing the Sun to the unilluminated hemisphere. Still, the atmosphere of Uranus showed almost no features during the Voyager 2 flyby in 1986. Voyager 2 also discovered a faint ring system about Uranus. In near-infrared, the Hubble can image faint cloud bands in the atmosphere.

Research at the Lawrence Livermore Lab suggests that pressures deep with within Uranus may result in an ocean of liquid diamond at the base of the mantle as carbon atoms form the tetrahedral arrangement we see in diamonds.

While Uranus has 27 known moons, none are particularly large. They also have quite dark surfaces and cannot be seen from Henize. The names of the moons come from characters in works by Shakespeare and Alexander Pope.

  • Uranus
  • Uranus Diagram
  • Uranus Symbol
Orbit Specifications
Semi-major axis 2.88 x 109 km
19.229 AU
Eccentricity 0.047
Orbital Period 84.02 yr
Sidereal Rotation 17.24 hr retrograde
Physical Characteristics Specifications
Mean radius 25,362 km
4.007 Earths
Mass 8.681 x 1025 kg
14.536 Earths
Mean density 1.27 g/cm3
Surface gravity 8.69 m/s2
0.886 g
Axial tilt 97.77°