Uranus
Uranus' Moons
Uranus was the first planet to be discovered in modern history.
It was actually discovered by accident in 1781 by William Herschel.
Like the other gas giants, Uranus has a very thick cloud cover
and an atmosphere made up mostly of hydrogen, helium, methane, and ammonia. The
trace amount of methane is what gives Uranus and its twin, Neptune,
their blue color. Unlike Saturn and Jupiter,
Uranus has a different internal structure.
The core of Uranus is probably composed of liquid rock. Then,
farther up, the liquid rock slowly gives way to an ocean made mostly of hydrogen,
helium, and water, with small amounts of ammonia and methane. This "ocean" accounts
for most of Uranus's bulk. Then, the water slowly thins out into the bland, almost
featureless atmosphere.
Uranus also has a system of about 11 rings - not nearly as
large as Saturn's. Nine were found when Uranus passed in front of a bright star,
the rings causing the star to temporarily disappear when they passed in front
of it. This was the first time astronomers had detected rings around any planet
other than Saturn. It was the first time, also, that astronomers had detected
thin rings around any planet. The other two rings were found when Voyager
2 passed by.
Uranus also has known moons,
most of which little is known about.
Uranus has two main unique features. First, there is absolutely
no detail in the cloud cover. Only when pushed to the maximum level of color
enhancement and contrast on computers do scientists start to see small swirls
in the atmosphere.
Second,
Uranus is the only planet rotates on its side. This produces the strangest seasons
of any planet in the solar system. For 21 years, Uranus's moons are seen as one
would view a dart board, with one pole facing the sun. The next 21 years Uranus
has its side to the sun, and the moons move up and down across the equator. then
the cycle repeats itself starting with the other pole. Scientists aren't sure
why this is, but they think that a large body smashed into it with such force
that it pushed the planet over.
Uranus was named for the ancient Greek god of the heavens.
When Earth was first made, Uranus was the first thing she saw, and they fell
in love.
|
Mean Orbital Distance (106 km) |
57.91 |
108.2 |
149.60 |
227.92 |
778.57 |
1433.53 |
2872.46 |
4495.06 |
Average Orbital Velocity (km/s) |
47.87 |
35 |
29.78 |
24.13 |
13.07 |
9.69 |
6.81 |
5.43 |
Orbital Inclination (from
Earth's Orbit) |
7.00° |
3.4° |
0.0° |
1.850° |
1.304° |
2.485° |
0.772° |
1.769° |
Orbital Eccentricity |
0.2056 |
0.007 |
0.0167 |
0.0935 |
0.0489 |
0.0565 |
0.0457 |
0.0113 |
Equatorial Radius (km) |
2439.7 |
6051.8 |
6378.1 |
3397 |
71,492 |
60,268 |
25,559 |
24,764 |
Polar Radius (km) |
2439.7 |
6051.8 |
6,356.8 |
3375 |
66,854 |
54,364 |
24,973 |
24,341 |
Axial Tilt (from Earth's geographic
North) |
0.01° |
177.4° |
23.45° |
25.19° |
3.13° |
26.73° |
97.77° |
28.32° |
Mass (1024 kg) |
0.3302 |
4.87 |
5.9736 |
0.64185 |
1898.6 |
568.46 |
86.832 |
102.43 |
Density (water=1) |
5.427 |
5.243 |
5.515 |
3.933 |
1.326 |
0.687 |
1.27 |
1.638 |
Escape Velocity (km/s) |
4.3 |
10.36 |
11.19 |
5.03 |
59.5 |
35.5 |
21.3 |
23.5 |
Gravity (m/s2) |
3.70 |
8.802 |
9.78 |
3.716 |
23.1 |
9 |
8.7 |
11 |
Sidereal Rotation Period (hours) |
1407.6 |
-5832.5 |
23.9345 |
24.6229 |
9.9250 |
10.656 |
-17.24 |
16.11 |
Length of Day (hours) |
4222.6 |
2802 |
24 |
24.6597 |
9.9259 |
10.656 |
17.24 |
16.11 |
Tropical Orbital Period (days) |
87.968 |
224.7 |
365.256 |
686.980 |
4330.595 |
10,746.94 |
30,588.740 |
59,799.9 |
Average
Surface Temperature (Celsius) |
167° |
464° |
15° |
-65° |
-110° |
-140° |
-195° |
-200° |
Number
of Moons |
|
|
|
|
|
|
|
|
Rings? |
No |
No |
No |
No |
Yes |
Yes |
Yes |
Yes |
Discoverer |
Unknown |
Unknown |
Unknown |
Unknown |
Unknown |
Unknown |
William Herschel |
Johann Gottfried Galle |
Discovery
Date |
Prehistory |
Prehistory |
Prehistory |
Prehistory |
Prehistory |
Prehistory |
March 13, 1781 |
September 23, 1846 |

|