There swells my Wallpaper folder :) Thanks, work collegues already asked about it (Yes, my computer spends that much time on the desktop)

Looks to me like it's the artist's vision of Triton as it passes its Roche limit. Triton is on a "reverse" orbit compared to the spin of Neptune, so it's slowing down, and will eventually get pulled into the planet. As I understand it, the Roche limit is when a smaller planetary-type body is so close to a larger one that it's gravity is no longer sufficient to hold it together, and the larger body's power tears it apart. I'm sure wikipedia can explain it better, or maybe NASA has an entry on it. Here we go: http://imagine.gsfc.nasa.gov/docs/dictionary.html#R From that website, I quote: "Roche limit The smallest distance from a planet or other body at which purely gravitational forces can hold together a satellite or secondary body of the same mean density as the primary. At less than this distance the tidal forces of the larger object would break up the smaller object." (Hopefully listing the webpage is sufficient citation - I really don't feel like looking up MLA rules or whatnot.)