Uranus
Overview
The German born British Astronomer Frederick William Herschel discovered Uranus in 1781 with an aid of a telescope. It takes its name from the Greek God of the sky Uranus.
Uranus, an ice giant, is the seventh planet from the Sun, and it is the third largest in the solar system. Twenty-seven small moons and thirteen faint rings orbit this planet.
Most of it consists of dense icy water, methane, and ammonia with a small rocky core at the center. Methane gives this planet the blue-green color.
Interesting Facts
Unique Tilt:
What is unique about Uranus is its tilt. It has a tilt of 97° that makes its equator almost vertical to its orbital plane around the Sun as you can see in the picture below. The 97° tilt is possibly because of an impact with an earth-sized object long ago.
Its rotation is like a rolling ball on its orbital plane. Another oddity is its spin from east to west (like Venus).
Moons/Rings: It has 27 known moons, and they take their names from the characters of William Shakespeare and Alexander Pope. Uranus, like Saturn, has a ring system which consists of thirteen faint rings. Because of the extreme tilt, all moons of Uranus revolve around it vertically to its orbital plane.
Size: Its radius is 25,362 kilometers. It is four times wider than our earth. The picture below shows how its size compares with Earth.
Atmosphere: Its atmosphere consists of mostly hydrogen and helium with a small amount of methane and traces of water and ammonia.
Orbit: It orbits the Sun at an average distance of about 2.9 billion kilometers, which is almost 20 times the distance between the Earth and the Sun. Sunlight takes 2 hours and 40 minutes to travel from the Sun to Uranus.
Day and Year: It takes 17 hours to spin once on its axis, and it takes 84 earth years to complete an orbit around the Sun.
Sources:
- The Cambridge Guide to the Solar System by Kenneth R. Lang, Cambridge University Press.