METEORITES: HOW TO RECOGNIZE THEM TO OBSERVE THEM BETTER?
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Time to read 3 min
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Time to read 3 min
Delve into the captivating world of meteorites and explore their cosmic origins. Learn how to distinguish them from asteroids and identify them during your next celestial observations. Meteorites, extraordinary witnesses to the formation of our solar system, come largely from the asteroid belt between Jupiter and Mars. Astronomers carefully scrutinize their path near Earth to better understand our universe.
Every day, about 50 tons of space rocks reach our planet , mostly from this asteroid belt. Frequent collisions in this region scatter rock fragments into space, some of which eventually hit Earth and become meteorites after a journey of millions of kilometers.
At the origin of meteorites is an accumulation of dust so dense that small grains began to form masses, even planets! Chondrules, small silicate balls dispersed in the matrix of meteorites, whose origin remains mysterious, agglomerated to form meteoroids. They result from the solidification of molten droplets during high-temperature events, probably the oldest solids in the solar system.
Meteoroids enter the Earth's atmosphere at speeds ranging from 11 to 72 kilometers per second , creating luminous phenomena known as meteors. As they enter the atmosphere, they heat up, melt, and lose mass, forming a characteristic fusion crust. A meteorite is a space rock (meteoroid or asteroid) that has naturally reached Earth after passing through the atmosphere.
Meteorites differ from asteroids in their trajectory and composition. Asteroids, mainly composed of rocks, metals and ices, are celestial bodies located mainly in the main asteroid belt between Mars and Jupiter, as well as in the Kuiper belt beyond Neptune. These asteroids are remnants of the protoplanetary disk that gave birth to the eight planets of the solar system.
Meteorites, on the other hand, are extraterrestrial fragments that have passed through the Earth's atmosphere. Originally, a meteor may be a fragment of an asteroid, called a meteoroid, often resulting from the collision of two asteroids in space. When this meteoroid enters the Earth's atmosphere at high speed, it heats up and burns, creating a luminous trail known as a shooting star or meteor. In some cases, part of the meteoroid manages to survive atmospheric reentry and reaches the Earth's surface, becoming a meteorite. This distinction between meteorites and asteroids is therefore linked to their path and their transformation when they come into contact with the Earth's atmosphere.
Identifying a meteorite can be difficult because of their similarity to terrestrial rocks. However, some unique characteristics, such as their fusion crust and metallic composition, allow them to be distinguished. When they enter the atmosphere, meteorites undergo a process of heating, fusion and vaporization of their surface. This phenomenon stops at different altitudes depending on the mass of the celestial object. Those that reach the ground all have a thin fusion crust a few millimeters thick, which is the first way to differentiate them from terrestrial rocks. If their fall is recent, they can appear black. The appearance of meteorites, whether matte, shiny or with a slight metallic sheen, varies depending on their type (chondrite, achondrite or ferric). They oxidize over time and take on a brownish tint. This coloring can fade on one side due to erosion, which then makes the meteorite more difficult to distinguish from other stones.
Meteorites are fascinating pieces of our solar system's history. By studying their composition and origins, scientists enrich our understanding of the universe. They tell us about how planets and stars formed, and the processes that shaped our solar system billions of years ago. Although they generally pose no danger when they fall to Earth, they continue to arouse the interest and wonder of astronomy enthusiasts.
Explore the mysteries of the universe through these celestial visitors and take the opportunity to participate in the search for meteorites. Each discovery opens a window on the origins of our solar system and life on Earth. They continue to fuel our imagination and enrich our knowledge of the universe. They are regularly found on Earth, and many auctions are organized where some are sold at high prices, proof that these small fragments of space make many people dream.
And you, what would your reaction be if you had the chance to find a meteorite?
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