James Webb Data Recasts 210-Mile Nereid as Neptune Moon Survivor, Not Kuiper Belt Capture
Updated
Updated · CNN · May 20
James Webb Data Recasts 210-Mile Nereid as Neptune Moon Survivor, Not Kuiper Belt Capture
3 articles · Updated · CNN · May 20
A new Science Advances study says Nereid may be the only intact moon left from Neptune’s original satellite system after Triton’s arrival more than 4 billion years ago.
James Webb infrared data from a 10-minute, 40-second observation found Nereid’s surface is water-rich, relatively bright and contains some CO2 — a composition unlike 54 compared Kuiper Belt objects.
Computer simulations showed that when Triton survives capture, one or more distant moons also survive about 25% of the time, supporting a scenario in which Nereid was scattered into its current eccentric orbit.
That would overturn the long-held view that Nereid, about 210 miles wide, was itself a captured Kuiper Belt object and instead make it a rare witness to Neptune’s early moon system.
Researchers said further James Webb observations could test the idea, but a definitive answer would likely require a Neptune mission; Voyager 2 remains the only spacecraft to have visited.
Triton’s violent arrival shattered Neptune's past. What happens when this moon inevitably crashes into the planet?
Webb's data suggests Nereid is a native moon. Does this discovery change how we view planetary system formation?
Nereid survived Neptune's ancient 'moonpocalypse,' but where are the remains of its lost sibling moons?