Meteorites: Messengers from Space and Witnesses of the Solar System

Origin and Classification

Meteorites are fragments of celestial bodies, mainly from asteroids (small rocky or metallic bodies in the Solar System), and more rarely from the Moon and Mars. They are classified into three main categories: stony meteorites, iron meteorites, and stony-iron meteorites (metal + silicates).

Meteorites contain silicates, oxides, and metals such as iron and nickel. Isotopic analysis allows us to trace their age and origin, providing insights into the first billion years of the Solar System (solar System).

The fall of meteorites on Earth provides valuable information about planetary formation and the history of the Solar System. Some fragments, called carbonaceous chondrites (meteorites rich in organic compounds), contain primitive organic molecules, testifying to prebiotic chemistry.

Stony Meteorites

Stony meteorites, or chondrites, are the most common, accounting for about 86% of all observed falls. They are mainly composed of silicates and formed during the first millions of years of the Solar System.

Main Composition

Olivine, pyroxene, as well as inclusions of metal and iron sulfide.

Iron Meteorites

Iron meteorites, or siderites, are mainly composed of iron and nickel. They generally come from the cores of differentiated asteroids that have been broken by collisions.

Main Composition

Iron-nickel alloy (mainly in the form of kamacite and taenite).

Stony-Iron Meteorites

Stony-iron meteorites, or lithosiderites, have a composition of equal parts stony and metallic materials. They are rare and come from the intermediate zone between the core and mantle of differentiated asteroids.

Main Composition

Mixture of silicates and iron-nickel alloys, often with distinctive crystalline structures.

Examples and Characteristics of Famous Meteorites

The following meteorites are among the most famous and well-studied. They provide valuable information about the history of the Solar System, the composition of celestial bodies, and the geological or atmospheric processes associated with their fall to Earth.

The table below shows their name, year of fall or discovery, main type, and a brief comment on their scientific or historical interest.

• NASA (new window).

Martian Meteorites

Martian meteorites are fragments of the surface of Mars that were ejected following meteoritic impacts. Their chemical composition, particularly the trapped gases (rare gas isotopes trapped in minerals) and Martian minerals, confirms their origin. These meteorites provide crucial information about Martian geology, the volcanic history of Mars, and the possible presence of water in the past.

The classification of Martian meteorites mainly includes three types: basaltic, sedimentary, and pyrogenic. The study of their radiometric age allows us to reconstruct the chronology of Martian geological processes over billions of years.

• Source: Lunar and Planetary Institute – Martian Meteorites (new window), NASA (new window).

Lunar Meteorites

Lunar meteorites are fragments of the Moon ejected by powerful impacts. Their geochemical and isotopic analysis shows a composition similar to the rocks brought back by the Apollo and Luna missions. These meteorites provide a valuable way to study the Moon without the need for a dedicated space mission.

They contain minerals such as plagioclase, pyroxene, and olivine. The study of their structure and radioactive isotopes allows us to date impact events on the Moon and better understand the history of its crust, volcanology, and overall formation.

• Source: Lunar and Planetary Institute – Lunar Meteorites (new window), NASA (new window).