Uranus is the seventh planet
from the Sun and was discovered in 1781 by Astronomer William
Herschel. It is a gas giant, like Saturn and Jupiter, and
thus it has no solid surface. It's atmosphere is composed
of mainly hydrogen and helium, with a fair amount of methane,
with traces of water and ammonia. The methane is what
gives the planet is bluish greenish color. The planet is so far
from the Sun that it's orbits is once every 84 years.
Uranus' axis is almost horizontal, meaning that it is as if it
has been flipped on its side. This is an extremely unusual
axis and is thought to be the result of a collision with a large
planet size body early in Uranus' history. Uranus has a
magnetic field almost 50 times more powerful than that on Earth.
Due to Uranus' distance from the Sun, there is little
temperature variation. The temperature at the cloud tops
is -216ºC (-357ºF).
Since Uranus is tipped on its side, the rings are perpendicular
to its path around the Sun, an odd configuration. There
are a total of eleven rings surrounding Uranus. The outer
10 are dark and thin. The innermost ring is broad and
diffuse.
Uranus has 27 known moons, with Oberon and Titania being the two
largest. All of the moons of Uranus are named after
characters of Shakespeare. The Voyager 2 spacecraft
helped locate 10 more moons that had been previously known.
Surprisingly enough, after Voyager 2, Hubble Space Telescope has
helped to discover a number of very small moons, some only 8 -
10 miles across. There is one area where there are so many
small moons orbiting Uranus close together that it is a mystery
that they do not collide into one another. The moon
Miranda is amongst the most unusual moons found anywhere in the
solar system. Of the largest moons, it is the smallest and
orbits the closest to Uranus. It has canyons 12 times
deeper that the Grand Canyon , with some surface features that
are very ancient and others that are relatively young.
| Mass (kg)
| 8.68 x 1025
|
| Diameter (km)
| 51118
|
| Mean density (kg/m3)
| 1290
|
| Escape velocity (m/s)
| 21300
|
| Average distance from Sun
| 19.19 AU (2,870,972,200 km)
|
| Rotation period (length of day in Earth days)
| 0.72 (17.9 Earth hours)(retrograde)
|
| Revolution period (length of year in Earth days)
| 30,685 (84 Earth years)
|
| Obliquity (tilt of axis degrees)
| 97.9
|
| Orbit inclination (degrees)
| 0.77
|
| Orbit eccentricity (deviation from circular)
| 0.047
|
| Mean temperature (K)
| 59
|
| Visual geometric albedo (reflectivity)
| 0.56
|
| Atmospheric components
| 83% hydrogen,
15% helium,
2% methane (at depth)
|
| Rings
| Uranus has a system of narrow, faint rings.
Ring particles are dark, and could
consist of rocky or carbonaceous material.
|
|
Image of Uranus
Photograph of
Moon Miranda
Infrared Picture of
Uranus Showing
Atmosphere and
Rings |
