Meteorite

A meteorite is a fragment of extraterrestrial matter—from an asteroid,a comet, the Moon, or Mars—that has passed through Earth’s atmosphere without burning up completely and has reached the Earth’s surface. These space rocks are direct samples of material from the early solar system, most of which date back 4.56 billion years.

The Major Families of Meteorites

Meteorites are divided into three major categories based on their composition. Chondrites are the most common (86%): they are primitive, undifferentiated rocks that have been preserved since the formation of the solar system. Achondrites originate from differentiated bodies— planets or massive asteroids — some of which, such as Martian meteorites, have a clearly identified origin. Metallic meteorites (iron-nickel) originate from the cores of fragmented asteroids.

How to Identify a Meteorite

Genuine meteorites have several distinctive characteristics. Most have a fusion crust—a blackened, glassy surface formed during their passage through the atmosphere. They are often denser than terrestrial rocks and can be attracted to a magnet if they contain metallic iron. Their surface sometimes features regmaglypts, thumb-shaped indentations left by ablation.

Importance in Astronomy

Meteorites are natural laboratories for chemists and planetary scientists. Isotopic analysis of meteorites allows scientists to accurately date the formation of the solar system and reconstruct the conditions of the protoplanetary disk. Some carbonaceous chondrites contain amino acids and other complex organic molecules, fueling debates about the chemical origin of life.

Concrete example

The ALH84001 meteorite, found in Antarctica in 1984 and identified as originating from Mars, was at thea major scientific controversy in 1996 when researchers suggested that it contained potential traces of fossilized microbial life. This interpretation remains highly debated today.

Frequently Asked Questions

Where are most meteorites found?

Antarctica is the region with the highest concentration of meteorites. The ice naturally preserves and concentrates them, and their dark color makes them easily identifiable against the white ice. Thousands of specimens have been collected there since the 1970s.

Are meteorites radioactive?

Some contain naturally occurring radioactive elements (like terrestrial rocks), but they are not dangerously radioactive. However, they may be hot to the touch immediately after falling, due to residual heat from their passage through the atmosphere.

Can you buy meteorites?

Yes, the trade in meteorites is legal in most countries, and there is an active market for collectors. Prices vary enormously depending on rarity, type, and origin—from a few euros per gram for common chondrites to several thousand for Martian or lunar meteorites.