Simplify the following text for a Grade 11 native English-speaking person.
Original: Unlike all other large planetary moons in the Solar System , Triton has a retrograde orbit , indicating that it was captured rather than forming in place ; it probably was once a dwarf planet in the Kuiper belt .
Simplified: Unlike all other large planetary moons , Triton has a retrograde orbit , showing that the moon was probably captured , and maybe was once a Kuiper belt object .