SmallBody

SmallBody is a term used in astronomy to refer to small Solar System bodies, the natural objects that orbit the Sun but are not planets, dwarf planets, or moons. The designation is widely used to group diverse objects whose orbits and physical properties differ from the major planets, yet provide crucial information about the early Solar System. The terminology is commonly abbreviated as SSSB or described simply as small bodies.

Small bodies include asteroids, most of which are rocky or metallic and largely reside in the inner Solar System, especially the asteroid belt between Mars and Jupiter. Comets are another major class; they contain volatile ices and develop comas and tails when near the Sun. The population also encompasses centaurs, which orbit between Jupiter and Neptune, and trans-Neptunian objects in the outer Solar System. Meteoroids are small fragments derived from larger bodies. Size ranges from meters to hundreds of kilometers, with some irregularly shaped due to collisions and weak self-gravity.

In orbital terms, small bodies can inhabit a wide variety of paths around the Sun and do not dominate or clear their neighborhoods, which is one reason they are distinguished from planets and dwarf planets. They are primarily discovered through astronomical surveys and undergo designation processes that begin with provisional names and often end with permanent numbers or named designations.

Small bodies are central to studies of Solar System formation, primordial material, and collisional evolution. Space missions have provided detailed close-up data on several examples, such as Rosetta's study of comet 67P/Churyumov–Gerasimenko, OSIRIS-REx on asteroid Bennu, and Hayabusa2 on asteroid Ryugu, contributing to our understanding of their composition and history.