Adrastea /ædrəˈstiːə/, also known as Jupiter XV, is the second by distance, and the smallest of the four inner moons of Jupiter. It was discovered in photographs taken by Voyager 2 in 1979, making it the first natural satellite to be discovered from images taken by an interplanetary spacecraft, rather than through a telescope.[6] It was officially named after the mythological Adrasteia, foster mother of the Greek god Zeus—the equivalent of the Roman god Jupiter.[7]