Ariel (Uranus I)
Ariel ("AIR ee el") is the twelfth of Uranus's known satellites.

Orbit:190,930 km from Uranus
Diameter:1158 km
Mass:1.27e21 kg
Discovered by:Lassell in 1851.

Ariel and Titania appear quite similar though Titania is 35% larger. All of Uranus' large moons are a mixture of about 40-50% water ice with the rest rock, a somewhat larger fraction of rock than Saturn's large moons such as Rhea.

Ariel's Surface:-
Ariel's surface is a mixture of cratered terrain and systems of interconnected valleys hundreds of kilometers long and more than 10 km deep. This is similar to, but much larger and more extensive than the situation on Titania. Some of the craters appear to be half-submerged. Ariel's surface is clearly relatively young (though older than some such as Enceladus); obviously some sort of resurfacing processes have been at work. Some ridges in the middle of the valleys are interpreted as upwellings of ice.

Ariel may have been hot inside long ago, but it's cold now. Perhaps the valleys are cracks which formed when Ariel froze.
Umbriel (Uranus II)
Umbriel ("UM bree el") is the thirteenth of Uranus's known satellites and the third largest.

Orbit:265,980 km from Uranus
Diameter:1170 km
Mass:1.27e21 kg
Discovered by:Lassell in 1851.

Umbriel and Oberon appear quite similar though Oberon is 35% larger. All of Uranus' large moons are a mixture of about 40-50% water ice with the rest rock, a somewhat larger fraction of rock than Saturn's large moons such as Rhea.

The Surface
Umbriel's heavily cratered surface has probably been stable since its formation. It has far more and larger craters than do Ariel and Titania.

Umbriel is very dark; it reflects only about half as much light as Ariel, Uranus' brightest satellite.

  • Difficulties:-
    1-Umbriel is significantly darker than the other large moons of Uranus. Why?

    2-What is the bright spot near the terminator in Umbriel?

    3-What caused the deep valleys and the resurfacing in Ariel Moon?

    [Sun-Mercury-Venus-Earth-Mars-Jupiter-Saturn-Uranus-Neptune-Pluto]
    [Source-About Team #C0115361-Comparison Tables-Earth Gelogical-Eclipses-Kinds of stars-Lunar Eclipse-Lunar Tides-Plate Tectonics-Quiz- Planets Mythology]
    Last Modified : 5 Sep. 2001
    Created By#C0115361 Team