Great Dark Spot. Voyager 2 image of the Great Dark Spot on Neptune, photographed on 22 August 1989 from a distance of 2.8 million km. The Spot is a giant storm system as large as Earth. The image shows feathery white clouds that overlie the boundary of the dark blue & light blue regions. The spiral (pinwheel) structure of both the dark boundary & the white cirrus clouds suggest a storm system rotating counter-clockwise. Periodic small- scale patterns in the white cloud, possibly waves, are short-lived & do not persist from one Neptunian rotation to the next. The picture was taken by Voyager 2's narrow-angle camera through the clear & green filters.