Name. Sidereal Distance Diameter Surface. Volume. Mass. Density. Axial Force of Velocity period. from Miles. Earth=1. Earth=1. Earth=1. Earth=1. Rotation. gravity. in orbit. d. h. m. Earth. d. h. m. Fall: Miles per Miles. Feet in hour. 1 sec. MOON 27 7 43 237,300 2,160 0.074 0.02034 0.0128 0.63 27 7 43 2.48 2,273 SATELLITES OF MARS. Name. Discoverer. Mean Sidereal Diameter. Maximum Apparent distance period. Miles. elongation. star from d. h. m. ″ magnitude. Mars. Miles. 1. PHOBOS A. Hall, August 6,000 0 7 39 7 12 11½ 17, 1877. 2. DEIMOS A. Hall, August 15,000 1 6 18 6 32 13½ 11, 1877. SATELLITES OF JUPITER. Name. Discoverer. Mean Sidereal Diameter. Apparent Apparent distance period. Miles. diameter star from d. h. m. of Jupiter magnitude. Jupiter. seen from Miles. satellite. ° ″ 5. Barnard ....... 0 11 49 ? ..... .... 1. IO ............... 267,000 1 18 29 2,390 19 49 7 2. EUROPA Galileo, January 425,000 3 13 13 2,120 12 25 7 7-13, 1610. 3. GANYMEDE ............... 678,000 7 4 0 3,980 7 47 6 4. CALLISTO ............... 1,192,000 16 18 5 2,970 4 25 7 SATELLITES OF SATURN.