Amalthea is Jupiter's third innermost known moon. Amalthea's orbit is about 112,000 miles from Jupiter. Amalthea has a diameter of 117 miles. The name Amalthea comes from a nymph who nursed the infant Jupiter with goats milk. Amalthea was discovered in 1892 by Barnard. Amalthea has a mass of 3.5e18kg.