Meteoroid
A meteoroid is a small, rocky or metallic object in space, typically a fragment from an asteroid or a comet. These objects range in size from tiny dust particles to objects up to about 10 meters in diameter. When these bodies enter Earth's atmosphere, they become visible as meteors, commonly referred to as "shooting stars." If a meteoroid survives its fiery passage through the atmosphere and lands on Earth, it is then called a meteorite.
History and Discovery
The study of meteoroids has a rich history intertwined with the observation of meteors. Ancient civilizations observed these phenomena, often interpreting them as omens or messages from the gods. However, scientific understanding began to develop in the 19th century:
- In 1803, French physicist Jean-Baptiste Biot studied the L'Aigle Meteorite fall, providing early evidence that meteorites come from outer space.
- The term "meteoroid" itself was coined in the 19th century to distinguish these objects from meteors and meteorites.
- The first meteorite fall with documented recovery was the Ensisheim Meteorite in 1492, although it wasn't until much later that the extraterrestrial origin of meteorites was accepted.
Characteristics and Composition
- Size: Meteoroids vary widely in size. Most are less than 1 meter in diameter, but some can be significantly larger.
- Composition: They are composed of materials similar to those found in asteroids and comets, including silicates, iron, nickel, and sometimes organic compounds.
- Origin: Meteoroids can originate from:
- Collisions in the asteroid belt.
- Comet debris, especially from their tails.
- Ejected material from planetary bodies due to impacts.
Impact on Earth
Most meteoroids burn up entirely upon entering Earth's atmosphere, creating a streak of light known as a meteor. However, larger meteoroids can survive this process:
- When a meteoroid lands on Earth, it becomes a meteorite. The study of these meteorites provides invaluable information about the early Solar System's conditions.
- Very rarely, large meteoroids or small asteroids can cause significant damage upon impact. An example is the Chelyabinsk Event in 2013, where a meteoroid exploded over Russia, causing injuries and property damage.
Scientific Importance
Meteoroids are critical for understanding:
- The composition of other celestial bodies.
- The formation and evolution of the Solar System.
- The potential threats from near-Earth objects.
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