Triton is the largest natural satellite of the planet Neptune, and the first Neptunian moon to be discovered. The discovery was made on October 10, 1846, by English astronomer William Lassell. It is the only large moon in the Solar System with a retrograde orbit, an orbit in the direction opposite to its planet's rotation. At 2,710 km in diameter, it is the seventh-largest moon in the Solar System.
urn:nasa:pds:context:target:satellite.neptune.triton
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