Planejote

Planejote is a term used in planetary science to describe a class of small celestial bodies that reside within a planetary system but neither form a planet nor are regarded as typical asteroids. The name combines the Greek root for “plane” with a suffix indicating diminutive or irregular form. Planejotes are distinguished by their intermediate mass, usually ranging from a few hundred meters to several tens of kilometers, and by their limited dynamical influence on neighboring bodies.

The primary criteria for classifying a body as a planejote are: (1) a well‑defined orbit that is not resonant with a major planet’s orbit; (2) a mass that has not cleared its orbital zone; and (3) the presence of an irregular shape or significant rotational variability. Objects that meet these criteria are typically found in the main asteroid belt, the Kuiper belt, or as co‑orbital companions to larger planets. Some planejotes are captured natural satellites that orbit a planet but lack the mass to be classified as a moon.

The concept emerged in the 1990s as astronomers investigated the diversity of bodies between planetary-sized objects and the conventional asteroid population. The first candidates were identified in the main asteroid belt through telescope surveys, and subsequent space missions provided detailed imaging of several planejotes. The study of planejotes offers insight into planetary formation and the dynamical evolution of minor bodies.

Current research focuses on mapping the distribution and composition of planejotes using infrared spectroscopy and high‑resolution imaging. Models of their collisional histories suggest that they may be remnants of a larger parent body or fragments produced by disruptive impacts. Understanding planejotes contributes to broader knowledge of the processes that shape small bodies in stellar systems and informs theories of planetary accretion, migration, and debris disk evolution.