Nereid, Neptune’s third-largest moon, stands out as a solitary survivor from an ancient group of moons. Recent insights from the James Webb Space Telescope suggest that Nereid might be the only moon left intact after a catastrophic event in our solar system’s early days.
Neptune, the most distant planet from the sun, hosts a quirky collection of moons. Unlike the orderly orbits of the moons around other gas giants like Jupiter and Saturn, Neptune’s moons have a chaotic system. Triton, the largest of these moons, is peculiar because it orbits Neptune in the opposite direction. This counter-orbiting suggests that Triton may not have formed with Neptune but instead was captured from the Kuiper Belt, a distant region filled with icy objects.
New research indicates Nereid’s formation story may differ from earlier beliefs, which suggested it was also a captured Kuiper Belt object. The James Webb Telescope’s data show that Nereid has a unique surface composition, rich in water and CO2, unlike any Kuiper Belt objects we know of. Matthew Belyakov, a planetary science graduate student, states that “Nereid is the only intact survivor” from a time when Neptune had a different system of moons.
According to Belyakov, other inner moons have been significantly altered by impacts and gravitational forces, making them look like “disrupted rubble piles.” Simulations reveal that if Nereid did survive Triton’s entry into the Neptunian system over 4 billion years ago, it likely escaped the chaos that affected the other moons.
Historical context strengthens this new hypothesis. In its early years, when Triton crashed into Neptune’s original moon system, some moons may have been destroyed or thrown out. Belyakov’s simulations showed that often, moons could escape this destruction, with Nereid emerging as one such lucky body.
The findings have galvanized interest in Nereid. Carolyn Porco, a renowned planetary scientist, lauds the implications of the study. Regular observations with the Webb Telescope could deepen our understanding of Nereid and the formation of moons around ice giants. Leigh Fletcher, a professor of Physics, echoed these sentiments, suggesting that more research could unearth finer details about Nereid’s origins.
Currently, the only clear image of Nereid dates back to 1989, captured by NASA’s Voyager 2. As we wait for further mission proposals to study Neptune, these findings remind us of the past mysteries that still linger in our solar system.
