THE first complete images of Neptune’s outer rings to be taken in over a decade show that some parts of them have dramatically deteriorated and one section is close to disappearing altogether.

The Voyager 2 spacecraft first photographed the rings in 1989. The images showed four bright arcs in the faint outermost “Adams” ring. These arcs spanned only about one-ninth of the ring in total. In 2002 and 2003, Imke de Pater of the University of California, Berkeley, and colleagues used the 10-metre Keck telescope in Hawaii to look at the ring again. They have now analysed the images and…