meteoriitin

Meteoriitin is a naturally occurring solid object of extraterrestrial origin that survives entry through a planet’s atmosphere and lands on its surface. Most meteoriitin are fragments of asteroids, though a smaller number originate from the Moon or Mars. They vary greatly in size, from tiny grains to hefty masses weighing many tons, with a subset reaching inhabited areas.

Meteoriitin are broadly categorized by their composition into three main groups: stony meteorites, iron meteorites, and stony-iron meteorites. Stony meteorites are further divided into chondrites, which contain primitive spherical grains called chondrules, and achondrites, which have undergone differentiation or melting. Iron meteorites consist mainly of metallic iron-nickel, while stony-iron meteorites blend rock and metal. These materials provide clues about the early solar system and planetary formation.

Identification and features: fresh meteoriitin often display a dark, glassy fusion crust formed during atmospheric passage and may show surface impressions known as regmaglypts. The interior composition is determined through petrographic analysis, isotopic dating, and trace-element studies. The age of many meteorites traces to the early solar system, about 4.5 billion years ago, making them valuable records of planetary formation.

Scientific importance and findings: meteoriitin help scientists study solar system history, early oxidation processes, and planetary differentiation. The distribution of meteorite finds is uneven, reflecting both atmospheric survivability and the likelihood of discovery. Notable meteorites include iron finds from Campo del Cielo, the Allende meteorite (a carbonaceous chondrite), and recent fall events that have aided research and education.

See also: meteor, meteor shower, asteroid, impact crater.