Overview

Carme is an irregular, retrograde moon of Jupiter that orbits far from the planet in a tilted, retrograde path. It was discovered in July 1938 by the American astronomer Seth Barnes Nicholson while working at the Mount Wilson Observatory. Carme is non-spherical and relatively small compared with Jupiter's major moons; its surface and precise composition are not well constrained by current observations, but it is described generally as a dark, primitive body typical of the outer irregular satellites.

Orbit and physical characteristics

Carme follows a retrograde orbit, meaning it moves around Jupiter in the opposite direction of the planet's rotation. Its semi-major axis places it at roughly 23–24 million kilometres from Jupiter, and its orbital inclination is near 165° relative to Jupiter's equator. These orbital parameters place Carme among the outer irregular satellites whose paths are strongly affected by solar and planetary perturbations; as a result, its precise orbital elements vary over time.

Origin and the Carme group

Carme gives its name to the Carme group, a set of small, retrograde moons that share similar orbits and spectral properties. The members of this group are widely believed to be fragments of a single progenitor body — a captured asteroid or primitive object that was broken up by a collision early in Jupiter's history. This common origin hypothesis explains the clustering in orbital distance, inclination and surface reflectance among the group members.

Naming and historical notes

After its discovery Carme was provisionally designated Jupiter XI. Between 1955 and 1975 it was sometimes referred to by the informal name "Pan"; that name was later assigned to a different, inner moon of Saturn, so the Jovian satellite received the official name Carme in 1975. The name Carme derives from Greek mythology — she is associated with figures connected to Zeus in some sources, and is named in the context of the goddess Britomartis and the god Zeus in classical tradition.

Scientific importance and observation

Although small and faint, Carme and the other irregular satellites are important for studies of planetary capture, collisional evolution, and the population of small bodies in the outer Solar System. Observations of their colours and spectra help astronomers infer links to asteroid classes and to test models of capture and fragmentation. Continued monitoring is necessary to track orbital changes caused by solar and planetary perturbations and to refine our understanding of the group's origin and physical properties.

  • Historic informal name: Pan (1955–1975)
  • Modern note: the name Pan now designates a moon of Saturn
  • Discovery and observatory: Mount Wilson Observatory and Seth B. Nicholson