Small Bodies and Debris
The leftover building blocks of the Solar System, asteroids, comets, distant icy worlds, meteorites, and dust, that preserve a record of its origin.
Definition
Small bodies and debris are the asteroids, comets, trans-Neptunian objects, meteoroids, and interplanetary dust that remain from the formation of the Solar System and were not incorporated into planets.
Scope
This area covers the small bodies and particulate debris of the Solar System: rocky and metallic asteroids, volatile-rich comets, the trans-Neptunian objects of the Kuiper Belt and beyond, and the meteorites and interplanetary dust that reach Earth. It treats their physical properties, dynamical populations and evolution, collisional and outgassing processes, and their value as relatively unprocessed samples of the early Solar System, along with the impact hazard some pose.
Sub-topics
Core questions
- What are the compositions and structures of asteroids, comets, and trans-Neptunian objects?
- How are these populations organized dynamically, and how do they evolve and interchange?
- What do small bodies and meteorites reveal about conditions in the early Solar System?
- How and how often do small bodies impact planets, and what hazard do they pose?
Key theories
- Small bodies as primitive remnants
- Asteroids, comets, and trans-Neptunian objects are leftover planetesimals that never grew into planets, preserving primordial materials and recording the Solar System's formation conditions.
- Dynamical sculpting of small-body populations
- Resonances with the planets and the migration of the giants cleared, transported, and trapped small bodies, shaping the structure of the asteroid belt and Kuiper Belt.
Clinical relevance
Small bodies are the most accessible primitive material in the Solar System, are sampled directly by meteorites and return missions, delivered volatiles to the early planets, and include the near-Earth objects relevant to planetary defense.
History
The first asteroid, Ceres, was discovered in 1801, and the study of small bodies expanded with the recognition of comet reservoirs, the 1992 discovery of the first Kuiper Belt object beyond Pluto, and modern surveys cataloguing hundreds of thousands of objects. Spacecraft encounters and sample-return missions have turned several small bodies into ground-truth laboratories.
Debates
- Asteroid-comet continuum
- The discovery of active asteroids and dormant comets blurs the once-clear line between rocky asteroids and icy comets, complicating their classification and dynamical histories.
Key figures
- William Bottke
- Alessandro Morbidelli
- Richard Binzel
- David Jewitt
Related topics
Seminal works
- bottke2002
- morbidelli2008
Frequently asked questions
- What is the difference between an asteroid and a comet?
- Asteroids are mostly rocky or metallic bodies from the inner Solar System, while comets are icy bodies from colder regions that release gas and dust, forming a tail, when they approach the Sun.
- Why do scientists study small bodies?
- Because they are leftover from the Solar System's birth and have changed relatively little, so they preserve clues about the materials and conditions from which the planets formed.