Amalthea
Amalthea is an inner irregular satellite of Jupiter, measuring 250 km across and is noted for its red color.
Amalthea was discovered by Edward Emerson Barnard on 9 September 1892, named after a nymph in Greek mythology.
Discovery E. E. Barnard, 9 September 1892
Primary body Jupiter
Periapsis 181150 km
Apoapsis 182840 km
Mean orbit radius 181365.84 km
Eccentricity 0.00319
Orbital period 11h57m23s (0.49817943d)
Average orbital speed 26.57 km/s
Inclination 0.374° (to Jupiter's equator)
PHYSICAL CHARACTERISTICS
Dimensions 250×146×128 km
Mean radius 83.5 km
Volume 2.43×106 km3
Mass 2.08×1018 kg
Mean density 0.857 g/cm3
Surface gravity 0.02 m/s2
Escape velocity 0.058 km/s
Rotation period synchronous
Axial tilt zero
Albedo 0.09
Mean surface temperature 120°K
Apparent magnitude from Earth 14.1