Discover some definitions of terms that are addressed in the exhibition.

Achondrites: a group of stony-iron meteorites originating from the mantle and most often from the crust of a differentiated asteroid.

Asteroid: a small, rocky body orbiting in the inner Solar System. The majority of asteroids are grouped together in a “belt”, between Mars and Jupiter.

Breccia: rock composed of rock fragments of various origins, which are assembled together. Asteroid impacts with other asteroids or Earth generate impact breccias.

Chondrules: beads of silicates and iron metal, formed within the first million years of the Solar System. Chondrules, which are tenths of millimetre-sized, are chondrites’ most prominent components.

Chondrites: the most common type of meteorites, which is divided into ordinary chondrites, carbonaceous chondrites and enstatite chondrites. Primarily composed of chondrules, their chemical composition is similar to that of the sun.

Fall: a meteorite whose arrival has been witnessed by a viewer. Falls are opposed to finds.

Comet: a small, outer Solar System body, composed of rock and ice. As it gets closer to the sun, the cometary ice evaporates, forming an impressive tail.

Fusion crust: one millimetre-thick, glassy coating that is formed when meteorites enter the atmosphere. The fusion crust enables one to distinguish freshly fallen meteorites from terrestrial rocks.

Differentiation: the geological process consisting in the gravitational segregation of the metal iron and rocks within a melted celestial body. The metal (mainly iron) will eventually form the core of the body.

Shooting star: the luminous phenomenon that is produced when a micrometeoroid enters the atmosphere at hypervelocity.

Presolar grain: microscopic stardust that is found in very small amounts in certain chondrites. Formed in stars pre-dating our Sun, they have survived the Solar System’s formation.

Hypervelocity or cosmic velocity: the speed at which meteoroids enter Earth’s atmosphere. It ranges between 11 and 72 kilometres per second.

Meteor: the luminous phenomenon that is produced by a meteoroid entering Earth’s atmosphere at hypervelocity.

Meteorite: extraterrestrial rock that is found on Earth’s surface.

Meteoroid: the name given to a stone travelling through the Solar System. Meteoroids are fragments of asteroids, comets or planets.

Solar system: the set of celestial bodies orbiting the Sun.

Find: a meteorite that has been found, either randomly, or during a systematic search expedition.