Triton completes one rotation on its axis in the same amount of time that it takes to circle Neptune, 5.88 Earth days. Because the rotation rate is synchronized with its orbital period, the same hemisphere always faces Neptune. Because of its retrograde orbit, Triton is spiraling slowly toward Neptune.
Triton is roughly the size of Earth's Moon.
Because Triton's size is uncertain, the Voyager flight team has prepared primary and alternative designs for some observations. The best Voyager images of Triton are expected to show features smaller than one mile. Scientists hope that Voyager 2's cameras will be able to see through Triton's atmosphere to the surface, where there is methane frost or ice and solid or liquid nitrogen. Small quantities of methane may also be dissolved in ponds of liquid nitrogen. On the dark side of Triton, Voyager 2 will look for temperature differences that may indicate the existence of liquid bodies.