Meteoroids, Meteorites & Impact Processes: Structures & Vocabulary

A meteoroid is a small solid body moving through space; a meteor is the luminous atmospheric phenomenon produced when such material enters an atmosphere at high speed; a meteorite is material that survives passage and reaches the ground. Large impacts are governed by kinetic energy and can reshape planetary surfaces globally or locally.

Impact energy scales with one-half mass times velocity squared, so speed strongly affects consequences. Hypervelocity impacts behave differently from ordinary low-speed collisions because pressures exceed rock strength by orders of magnitude. Atmospheric drag can fragment smaller objects, while very large bodies retain enough momentum to reach the surface.

Meteor networks triangulate atmospheric paths, recovered meteorites reveal primitive and differentiated asteroid material, and impact craters contain diagnostic features such as shocked minerals, melt, ejecta blankets, and central peaks. The Chicxulub structure and global boundary deposits link a large impact to the end-Cretaceous mass extinction.

Atmospheric entry involves velocity, mass, shape, strength, trajectory angle, drag, ablation, fragmentation, and shock formation. Impact craters include transient cavities, ejecta, rims, and—at larger sizes—central peaks or rings. Meteorites are classified by composition and differentiation history.