# Ariel (GIF, 196K)

Uranus I

Ariel [AIR-ee-al] is a relatively small satellite and is the brightest moon of Uranus. The surface is pock-marked with craters, but the most outstanding features are long rift valleys stretching across the entire surface. Canyons much like the ones on Mars appear in the pictures. The canyon floors appear as though they have been smoothed by a fluid. The fluid could not have been water because water acts like steel at these temperatures. The flow marks might have been made by ammonia, methane or even carbon monoxide.

## Ariel Statistics

    Discovered by ............................... William Lassell
    Date of discovery ...................................... 1851

    Mass (kg) .......................................... 1.27e+21
    Mass (Earth = 1) ................................. 2.1252e-04
    Equatorial radius (km) ................................ 578.9
    Equatorial radius (Earth = 1) .................... 9.0765e-02
    Mean density (gm/cm^3) ................................. 1.56

    Mean distance from Uranus (km) ...................... 191,240
    Rotational period (days) ........................... 2.520379
    Orbital period (days) .............................. 2.520379
    Mean orbital velocity (km/sec) ......................... 5.52

    Orbital eccentricity ................................. 0.0034
    Orbital inclination .................................... 0.31°

    Escape Velocity (km/sec) .............................. 0.541

    Visual geometric albedo ................................ 0.34
    Magnitude (Vo) ........................................ 14.16

Uranus Miranda Umbriel

##### Author: Calvin J. Hamilton.