Ganymede

Largest moon in the solar system. Larger than the planets Mercury and Pluto and 3/4 the size of Mars. The Hubble Space telescope found a thin oxygen atmosphere, although small green men were nowhere to be found. In December 2000 scientists reported to have found oceans of salt water beneath the upper layer of ice. The high concentration of salt together with heat from radioactivty would make it possible for the water not to freeze.

Discovery:                             Jan 11, 1610 by Galileo Galilei
Diameter (km):                         5,268                 
Mass (kg):                             1.48e23 kg 
Mass (Earth = 1)                       0.0247 
Surface Gravity (Earth = 1):           0.145
Mean Distance from Jupiter (km):       1,070,000
Mean Distance From Jupiter (Rj):       15.1 
Mean Distance from Sun (AU):           5.203
Orbital period (days):                 7.154553 
Rotational period  (days):             7.154553 
Density (gm/cm3)                       1.94
Orbit Eccentricity:                    0.002
Orbit Inclination (degrees):           0.183
Orbit Speed (km/sec):                  10.9
Escape velocity (km/sec):              2.74 
Visual Albedo:                         0.43
Subsolar Temperature (K):              156
Equatorial Subsurface Temperature (K): 117
Surface Composition:                   Dirty Ice

Data from NASA

In Greek mythology, a Trojan youth that was considered the most beautiful of all mortals. Zeus, king of the gods, fell in love with Ganymede one day as the boy was guarding his father's flock. Taking on the form of an eagle, Zeus descended from holy Mount Olympus and abducted the barely adolescent lad. Ganymede replaced Hebe, the goddess of youth, as cupbearer to the gods in exchange for a pair of immortal horses, or a golden vine. A constellation was created in the form of the eagle that carried off Ganymede. The story of Zeus and Ganymede, and many others like it, serve to illustrate the strong belief of the Ancient Greeks that homosexuality was as natural and beautiful as heterosexual love. Throughout the Middle Ages Ganymede was perceived as the personification of homosexual love.