The Origin and Formation of Meteorites

Abstract

The materials from which meteorites were formed have had a complex history, which is presented schematically in Fig. 98. The beginning is nucleosynthesis, i.e., the production of the chemical elements by nuclear processes under conditions of very high temperatures and pressure in the interior of stars. All of the elements originated from hydrogen through the addition of protons, neutrons, and electrons. Over time, these materials were distributed throughout interstellar space. A localized cloud of higher density could have formed and through a process referred to as gravitational collapse produced the solar nebula. With further contraction and increase in density, the nebula evolved into the Sun and numerous small solid bodies (planetesimals). In a final stage, many of the planetesimals combined to form a smaller number of larger bodies, the planets. In such a body, referred to as the meteorite parent body, the history of a meteorite as an isolated piece of rock actually begins. Later, separated from its parent body, presumably by an impact, the meteoroid began its life as a small body in its own orbit around the Sun.