The paths traced by Io (solid line, semi-major axis 5.9 RJ), Europa (dashed line, semi-major axis 9.5 RJ), and Ganymede (dotted line, semi-major axis 15.1 RJ) are marked on the image. Callisto (semi-major axis 26.6 RJ) is off the image to the east side, although the satellite did fall within the full microchannel plate field of view. At the time of this observation, Jupiter's equatorial radius corresponded to 23.9 arcsec.