Amalthea . Jupiter V . Amalthea [am-al-THEE-uh] is one of Jupiter's smaller moons. ... It was also the first moon of Jupiter to be discovered since Galileo's discovery of the four Galilean Moons in 1610. Amalthea is extremely irregular, having dimensions of about 270x165x150 kilometers in diameter. ... Discovered by . ... Topographic Map of Amalthea . ... As with all maps, it is the cartographer's interpretation; not all features are necessarily certain given the limited data available. ...