A full Neptune washes Triton's frozen surface with an indigo light, the only source of illumination on this now Triton's dark side. Fortuitous alignment of the Sun, Triton and Neptune causes this satellite's shadow to fall on Neptune's distant cloud tops 220 thousand miles away. This view is from within a deep, crater-like depression on Triton's northern hemisphere.

There are many such crater-like depressions on Triton's northern hemisphere, regularly spaced like dimples on a golf ball. While these depressions look like impact craters, their similar size and spacing suggest that they were created by some other process. Their origin is still unknown, but may involve local melting and collapse of the icy surface. The scarcity of impact craters suggest that this surface is relatively young by solar system standards, probably less than a few billion years old. The depression in this image is about 15 miles in diameter; the ridge on the horizon is approximately seven miles from the mesa in the foreground.