Neptune’s largest moon, Triton, is special for one big reason: it orbits backward. Almost every large moon in the solar system orbits in the same direction as its planet’s rotation, but Triton goes the opposite way. This suggests it wasn’t born around Neptune but was captured from the Kuiper Belt. Over time, this odd orbit is dragging Triton closer to Neptune, and one day—millions of years from now—it might break apart, forming a temporary ring system.