Voyager at Neptune

Late last August Voyager 2 flew by Neptune, the most remote object yet visited by a spacecraft and the culmination of a 12-year journey of exploration of the four giant planets. In a real sense Voyager has been writing the encyclopedia of the outer solar system over that last 12 years. For the latest volume I'd like to describe what we discovered last August, what we now understand, and what still puzzles us.