Metis . Jupiter XVI - 1979J3 . Metis [MEE-tis] is the innermost known satellite of Jupiter. ... Metis and Adrastea lie within Jupiter's main ring and may be the source of material for the ring. ... Galileo Image of Metis . ... Although Metis was discovered by Voyager, it was no more than a point of light on images. This Galileo image is the the first image of the small moon that shows its irregular shape. ... The longest dimension of Metis is approximately 60 kilometers (37 miles) across. ...