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What’s the difference between a meteoroid, a meteor, and a meteorite? Meteoroids: These rocks still are in space. Meteoroids range in size from dust grains to small asteroids. Meteors: When meteoroids enter Earth’s atmosphere (or that of another planet, like Mars) at high speed and burn up, the fireballs or “shooting stars” are called ...
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meteorite, any fairly small natural object from interplanetary space—i.e., a meteoroid—that survives its passage through Earth’s atmosphere and lands on the surface. In modern usage the term is broadly applied to similar objects that land on the surface of other comparatively large bodies. For instance, meteorite fragments have been found in samples returned from the Moon, and the robotic rover Opportunity has identified at least one meteorite on the surface of Mars. The largest meteorite that has been identified on Earth was found in 1920 in Namibia and was named the Hoba meteorite. It measures 2.7 metres (9 feet) across, is estimated to weigh nearly 60 tons, and is made of an alloy of iron and nickel. The smallest meteorites, called micrometeorites, range in size from a few hundred micrometres (μm) to as small as about 10 μm and come from the population of tiny particles that fill interplanetary space (see interplanetary dust particle).
Laboratory, astronomical, and theoretical studies show that most discrete meteorites found on Earth are fragments of asteroids that orbit in the inner portion of the main asteroid belt, between about 2.1 and 3.3 astronomical units (AU) from the Sun. (One astronomical unit is the average distance from Earth to the Sun—about 150 million km [93 million miles].) It is in this region that strong gravitational perturbations by the planets, especially Jupiter, can put meteoroids into Earth-crossing orbits. Not all meteoroids need to have formed in this region, however, as there are a number of processes that can cause their orbits to migrate over long time periods. Fewer than 1 percent of meteorites are thought to come from the Moon or Mars. On the other hand, there is good reason to believe that a significant fraction of the micrometeorites found drifting down through Earth’s upper atmosphere come from comets. Although evidence from studies of meteors suggests that a small fraction of the cometary material that enters Earth’s atmosphere in discrete chunks possesses sufficient strength to survive to reach the surface, it is not generally believed that any of this material exists in meteorite collections. For further discussion of the sources of meteorites and the processes by which they are brought to Earth, see meteor and meteoroid: Reservoirs of meteoroids in space and Directing meteoroids to Earth.
Meteorites traditionally are given the name of a geographic feature associated with the location where they are found. Until quite recently, there were no systematic efforts to recover them. This was largely because meteorites fall more or less uniformly over Earth’s surface and because there was no obvious way to predict where they would fall or could be found. When a meteorite was seen to fall or when a person chanced upon an unusual-looking rock, the specimen was simply taken to a museum or a private collector.
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In the 1930s and ’40s, enterprising meteorite collectors began crisscrossing the prairie regions of North America, asking farmers to bring them unusual rocks that they had found while plowing their fields. Prairie soil is largely derived from fine glacial loess and contains few large rocks. The collectors realized that there was a reasonable chance that any rocks the farmers unearthed would include meteorites.
A better approach to finding meteorites than searching places with few rocks, however, is to search places where they can accumulate over time—i.e., where the surface is quite old and rates of weathering are low. Because meteorites contain minerals, such as iron metal, that are easily weathered, they do not normally last long on Earth’s surface. Liquid water is one of the principal agents of weathering. In desert environments, where there is little water, meteorites survive much longer. Indeed, they tend to accumulate on the surface in arid regions if weathering rates are slower than the rates at which meteorites fall to Earth, provided that little windblown sand accumulates to bury them. Areas of the Sahara in North Africa and the Nullarbor Plain region in Australia have proved to be good places to look for meteorites. The most-successful collection efforts, however, have been in Antarctica.
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Apr 4, 2024 · Article. Vocabulary. Meteorites are space rocks that fall to Earth’s surface. Meteorites are the last stage in the existence of these type of space rocks. Before they were meteorites, the rocks were meteors. Before they were meteors, they were meteoroids. Meteoroids are lumps of rock or metal that orbit the sun.
A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon.
Jul 1, 2019 · Objects smaller than asteroids are called meteoroids, and they are usually much smaller – about the size of pebbles. Some meteorites may also come from Mars or the Moon. When the orbit or path of an asteroid or meteoroid crosses Earth, it starts its journey through the Earth’s atmosphere (meteor) until it lands on the surface (meteorite).
Meteoroid. A meteoroid shown entering the atmosphere, causing a visible meteor and hitting the Earth's surface as a meteorite. A meteoroid ( / ˈmiːtiərɔɪd / MEE-tee-ə-royd) [1] is a small rocky or metallic body in outer space . Meteoroids are distinguished as objects significantly smaller than asteroids, ranging in size from grains to ...
