A New Study on Neptune’s mysterious moon Nereid

Why in News?

A new scientific study using observations from National Aeronautics and Space Administration’s James Webb Space Telescope suggests that Neptune’s moon Nereid may be the only surviving original satellite of Neptune. The finding challenges the long-standing theory that Nereid was captured from the Kuiper Belt, similar to Neptune’s largest moon, Triton. 

Background

Scientists believe that during the early evolution of the outer Solar System, Neptune gravitationally captured Triton from the Kuiper Belt, a distant region filled with icy bodies and dwarf planets beyond Neptune’s orbit.

This capture is thought to have severely disrupted Neptune’s original moon system because Triton’s strong gravitational influence likely destabilised or destroyed many existing satellites.

Earlier theories suggested that Nereid was also a captured Kuiper Belt object. However, the new study proposes that Nereid may actually be an original moon of Neptune that managed to survive the chaos caused by Triton’s capture. 

Key Findings of the Study

• Data from the James Webb Space Telescope indicates that Nereid’s characteristics differ from typical captured Kuiper Belt objects.
• Researchers suggest Nereid likely formed around Neptune itself.
• Nereid may therefore represent the last surviving remnant of Neptune’s ancient original satellite system.

About Nereid

• Nereid is the third-largest moon of Neptune.
• It has a highly eccentric orbit, meaning its distance from Neptune changes significantly during its orbit.
• It was discovered in 1949 by astronomer Gerard Kuiper.

About Triton

• Triton is Neptune’s largest moon.
• It orbits Neptune in a retrograde direction, opposite to Neptune’s rotation.
• This unusual orbit strongly suggests it was captured rather than formed naturally around Neptune.
• Triton is considered one of the coldest known objects in the Solar System.

What is the Kuiper Belt?

The Kuiper Belt is a vast ring-shaped region beyond Neptune containing icy bodies, comets, small solar system objects, and dwarf planets such as Pluto. It is considered a remnant of the early Solar System.

Source: Space.com