Triton
Triton is the largest of Neptune's 13 moons and is unique due to its retrograde orbit, meaning it orbits Neptune in the opposite direction of the planet's rotation. Scientists believe Triton was a Kuiper Belt Object captured by Neptune's gravity millions of years ago.
Source: science.nasa.gov
APODs including "Triton"
Crescent Neptune and Triton
27/05/2023
Gliding through the outer Solar System, in 1989 the Voyager 2 spacecraft looked toward the Sun to find this view of most distant planet Neptune and its moon Triton together in a crescent phase. The elegant image of ice-giant planet and largest moon was taken from behind just after Voyager's closest approach. It could not have been taken from Earth because the most distant planet never shows a crescent phase to sunward eyes. Heading for the heliopause and beyond, the spacecraft's parting vantage point also robs Neptune of its familiar blue hue.