What are Meteors?

Most of us have looked up and the night sky and seen what is commonly called a falling, or shooting, star. These momentary streaks occur when meteors, objects generally ranging from the size of dust particles that might only be seen with a telescope or through binoculars, to fist-size masses, enter the Earth's atmosphere at speeds up to 44 miles per second and are ionized (or heated) to incandescence 50 to 75 miles above the Earth. Few of these objects survive their encounter with our atmosphere.

What we see here on Earth, mostly at night, is a streak of light that lasts about a half a second on the average. Generally speaking, the larger the material that enters the Earth's atmosphere the brighter the meteor. Brighter meteors will occasionally leave a smoke trail behind in their path lasting a few seconds; trails produced by very bright meteors, referred to as fireballs, may last minutes. Fireballs that appear to break up or produce sound are called bolides, from the Greek word bolis meaning missile.

What are meteorites?

Meteorites, the objects that we find on Earth that come space, originate mostly from asteoroids and a few from our own Moon, the planet Mars, and comets. They came to Earth after streaking through the sky as meteors. They are very unusual rocks that are mostly composed of stone with a nickel-iron matrix. To hold one in your hand is to hold some of the most ancient and primordial material of our solar system. In fact some meteorites predate the solar system, and are theorized to come from other star systems from across the Milky Way or perhaps even from another galaxy.

There are three main classes of meteorites:

Stone Meteorites

Stone meteorites make up the largest group accounting for approximately 92% of all meteorites. They are comprised chiefly of silicates, although they contain 5-15% nickel-iron and iron sulfide.

Iron Meteorites

Iron meteorites are nearly 100% nickel-iron and are therefore heavy and dense. Iron meteorites make up about 6.5% of all meteorites.

Stony-Iron Meteorites

Stony-irons, the rarest type, are a combination of stone and metal. They make up a mere 1.5% of all recovered specimens. While the outside looks like an iron meteorite, the inside is quite unique. There are two types of stony-iron meteorites, pallasites that display crystals of olivine, and mesosiderites that show irregular grains of nickel-iron in a stone matrix.

How rare are meteorites?

Since most meteors burn up in our atmosphere before reaching the ground (thus becoming a "meteorite"), very few actually arrive on Earth intact. Only a very small fraction of a meteoric falls are actually found. They arrive with no advanced warning, with most falling into the depths of our oceans. Very, very few falls are actually witnessed by people, and even fewer fall in areas where people can locate them. Because of the difficulty in finding and identifying meteorites, the few that actually make their way into museums and private collections are truly among the rarest items in the world.

Are there unique features found in meteorites that are not found in Earth rocks?

All meteorites have travelled to Earth from incredible distances, and as such all meteorites are in the very true sense of the word, alien. But there are chemical processes and unique materials in some meteorites that are not found in any Earth-born rocks. This would include the so called "Widmannstätten Pattern", a feature unique to iron meteorites that cannot even be replicated in the laboratory.

How do meteorites get their names?

Meteorites are usually named after the places where they are found. They are named after countries, geographical areas, and cities. An example of a meteorite that carries an unusual name are the Vaca Muerta (which means "dead cow") meteorites originally recovered along a cattle trail along with cow bones.

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