Edward Emerson Barnard discovers Amalthea, fifth moon of Jupiter

Background. Lick Observatory, located on Mount Hamilton in California, was the first permanently occupied mountain-top observatory in the world. Edward Emerson Barnard joined its staff in 1887. The observatory, managed by the University of California, provided the setting for Barnard's significant astronomical contributions, including his work with the 36-inch refractor telescope.

Discovery. On 9 September 1892, Barnard used the 36-inch refractor at Lick Observatory to identify Amalthea, the fifth moon of Jupiter. This was the first new Jovian satellite since Galileo's 1610 discoveries. Amalthea is the largest inner satellite, irregularly shaped, and reddish, with the third-closest orbit among known moons.

Significance. Amalthea's discovery was the last planetary satellite found by direct visual observation, as opposed to photographic or digital imaging. Barnard, recognized as a gifted observational astronomer, named the moon after Amalthea of Greek mythology. This event concluded a period of visual discovery that had lasted since the early 17th century.