Triton Orbits Neptune Backward, Pointing to Kuiper Belt Capture and a Billion-Year Inward Spiral
Updated
Updated · spacedaily.com · Aug 12
Triton Orbits Neptune Backward, Pointing to Kuiper Belt Capture and a Billion-Year Inward Spiral
1 articles · Updated · spacedaily.com · Aug 12
Summary
Triton remains the only large moon known to orbit opposite its planet’s spin, a retrograde path that strongly indicates Neptune captured it rather than forming it in place.
A 2006 model by Craig Agnor and Douglas Hamilton explains the capture: Triton likely arrived in a binary pair, and Neptune’s gravity split the two bodies, ejecting one and trapping the other.
Voyager 2’s 1989 flyby also found geysers on Triton despite surface temperatures near minus 391 degrees Fahrenheit, with scientists linking the activity to sunlight-driven pressure in buried nitrogen ice.
Because the captured moon moves backward, tidal forces are pulling it inward instead of outward, meaning Triton is expected over billions of years to be torn apart or collide with Neptune.