25 million km. This Voyager 2 image of Neptune shows the discovery of shadows in Neptune's atmosphere.

P-34668 Range : 25 million km. ( 16 million miles ) Smallest Resolvable Feature : 45 km or 28 miles This Voyager 2 image of Neptune, shot with a narrow angle camera, shows the discovery of shadows in Neptune's atmosphere. The shadows cast onto deep cloud banks by smaller elevated clouds. Located at about 68 degrees south latitude, they are the first cloud shadows ever seen by Voyager on any planet. The dark regions adjacent to the small bright clouds are believed to be shadows, because they are on the side of the cloud that is opposite to the incoming sunlight and because they lengthen in places where the sun lies closer to the horizon. Estimates of the height of these discrete clouds above the underlying cloud bank can be obtained by careful analysis of this data.