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News In Brief

Clear photos of Neptune pinpoint the planet's day

The clearest photographs yet of Neptune and its giant clouds have enabled scientists for the first time to determine the precise length of a day on the solar system's eighth planet - 17 hours and 50 minutes.

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The new photographs show three 5,000-mile-diameter cloud patches in Neptune's outer atmosphere in the planet's middle latitudes.

The clouds are believed to rotate at the same speed as the entire planet, so the photos ''allowed us to measure the length of the day on Neptune by watching cloud features move all the way around,'' Richard J. Terrile, a Jet Propulsion Laboratory scientist, said Wednesday.