Each day we feature a different image or photograph of our fascinating universe, along with a brief explanation written by a professional astronomer. The orbit of Amalthea is inside of these moons, and with its long axis always pointing toward Jupiter . It's dark surface color is probably due to sulfur being expelled from Io . Amalthea is not massive enough for its internal gravity to make it spherical. Amalthea was discovered in 1892 by Edward Barnard.
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