What Are Meteorites?

Meteorites are extraterrestrial rocks that strike the Earth’s surface. These chunks of space debris come in many shapes, sizes, and compositions. Humankind can learn much from meteorites about our solar system and its history.

Meteorites vary in composition depending on their origin and range in size from microscopic particles to large boulders. They can compose of iron-nickel alloys, stony materials, or a combination of both. When these objects enter Earth’s atmosphere at high speeds, friction produces heat that vaporizes some material as it enters Earth’s atmosphere and forms a gaseous trail called a meteor or shooting star, often visible in night skies.

There are three main categories of meteorites based on their chemical composition and structure: stony meteorites (“stone”), iron meteorites (“irons”), and stony-iron meteorites which contain both metal and stone). Stony meteorites are mostly silicates, while iron meteorites contain mostly metal alloys such as nickel-iron. Stony-iron meteorites have both; they contain varying amounts of stone material mixed with metal alloys.

These three classes can be further subdivided depending on the sample’s constituents. For instance, there are two possible classifications among stony meteorites: chondrites (which contain chondrules) and achondrites. Chondrules are small spherical objects found within some stones that indicate that the rock was once molten or partially melted due to high temperatures experienced during entry into Earth’s atmosphere.

Different meteorite samples also have individual characteristics that can help scientists identify them more easily. For example, some metallic irons may exhibit “widmanstatten lines,” which appear as alternating lines of a different color when viewed under a microscope due to the crystallization process that occurred during entry into Earth’s atmosphere.

Studying meteorites gives scientists invaluable insight into the solar system’s history and general clues about changes occurring in space over time. They hypothesize that meteorites can shed light on everything from planetary formation to the nature of extraterrestrial materials to the distribution of elements in the universe to the particle makeup of planets and moons beyond our own and even the presence of cosmic radiation in specific regions of the universe. With further meteorite studies, scientists can better understand how asteroids evolved and interacted with other celestial bodies to form habitable planets like Earth.

One benefit of studying meteorites is that scientists believe they have the potential for commercial applications. The high nickel content in many meteorites makes them invaluable as alloying elements when creating stronger, more durable metals. Most ancient civilizations have used meteorite fragments as ornaments and small sculptures as they offer an appealing artistic value that neither synthetic nor terrestrial samples possess.

If you come across an unusual rock, it might be a meteorite. The best way to identify a meteorite if you find one is by doing a combination visual examination for certain physical characteristics and testing its weight relative to size comparative (called “specific gravity”). The first thing to note is that meteorites typically have a black or brown fused crust. Typically, asteroidal rocks are denser, have higher magnetic susceptibility, and weather differently than their terrestrial counterparts.

Meteorites can also display regmaglypts, indentations that appear on the object’s surface due to its extreme entry velocity into Earth’s atmosphere and resulting melting due to air friction. To compare your sample with other known meteors, use terrestrial analogs or consult scientific databases such as the Meteoritical Society to verify your findings.