Neptune's moon Triton is currently getting closer and closer to the Roche limit. Predictions are that some 3.6 billion years from now, Triton will pass within Neptune's Roche limit. This will result in either a collision with Neptune's atmosphere or the breakup of Triton, forming a ring system similar to that found around Saturn. Bad news: We won't be around (duh!) and the Earth will have already become hot and Venus-like, courtesy of the Sun, which is still in the main sequence but getting hotter.