Trending Now - Neptune's Unique Moon Nereid Offers Insights Into Solar System

WHO:

Live Science - Matthew Belyakov, a graduate student in planetary science at Caltech, is the first study author.

Live Science - Konstantin Batygin, a noted moon dynamicist and Caltech professor, is part of Belyakov's team.

WHAT:

Live Science - Nereid, Neptune's third-largest moon, is suggested to be the only moon left over from the planet's formation.

Live Science - Nereid is 220 miles wide (350 kilometers).

Live Science - The study published in the journal Science Advances contradicts previous beliefs about Nereid's history.

Sky and Telescope - New research indicates that Triton or a Triton-like object may have disrupted Neptune's original moon system.

WHERE:

Live Science - The observations were made using the James Webb Space Telescope (JWST).

WHEN:

Live Science - The study results were published on May 20 in the journal Science Advances.

WHY:

Live Science - The previous assumption was that Nereid was captured by Neptune's gravity, which is now challenged by new data.

Live Science - The study aims to understand how moons around Uranus and Neptune form, as these planets are common types in the study of exoplanets.

HOW:

Live Science - JWST's observations confirmed that Nereid has a lot of water ice and provided a spectrum of light for analysis.

Live Science - The team ran simulations of Triton's capture from the Kuiper Belt and its effects on Neptune's existing moons.

Live Science - Belyakov's team plans to apply for higher-resolution observations using JWST's Near-Infrared Spectrograph (NIRSpec) in a future call for telescope observations.

(UPDATED May 22, 2026 21:31 UTC)

New research led by graduate student Matthew Belyakov at Caltech suggests that Nereid, Neptune's third-largest moon, may be the only moon remaining from the planet's formation, contradicting previous beliefs that it was captured by Neptune's gravity. The study, which also includes contributions from noted moon dynamicist Konstantin Batygin, utilized the James Webb Space Telescope to confirm that Nereid has significant amounts of water ice and ran simulations on the effects of Triton's capture from the Kuiper Belt on Neptune's moon system. Belyakov's team plans to apply for higher-resolution observations using the telescope's Near-Infrared Spectrograph in a future call for telescope observations.