Meteor
A meteor is what you see when a space rock falls to Earth. It is often known as a shooting star or falling star and can be a bright light in the night sky, though most are faint. A few survive long enough to hit the ground. That is called a meteorite, and a large one sometimes leaves a hole in the ground called a crater.
A rock that has not yet hit the atmosphere is called a "meteoroid". Meteoroids may range in size from large pieces of rock to tiny dust particles floating in space that did not form planets. When the meteoroids enter Earth's atmosphere they are usually going faster than the Earth's escape velocity of 13 km/sec or Mach 40. This makes them heat up and usually break apart. When the heat makes them glow, they are known as meteors.
Meteors are distinct from comets or asteroids, but some, especially those associated with meteor showers, are dust particles that came out of comets.
There are several types of meteorites including: stony, carbonaceous chondrites, and iron-nickel. Stony meteorites are named because they are largely made up of stone-like mineral material. Carbonaceous chondrites have a high carbon content. Iron-nickel meteorites are mostly iron often with significant nickel as well.
Meteorites were many during the Late Heavy Bombardment. Nowadays they sometimes hurt people and property. The 2013 Russian meteor event did the most damage. Large meteorite strikes may have played a part in several of the mass extinctions, and so indirectly on the course of evolution. (see K/T extinction event; List of extinction events; Chicxulub crater)
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Meteorite types
Chondrites
Chondrites are stony (non-metallic) meteorites that are as old as the Solar System: 4.55 billion years.[1] They sometimes contain amino acids and other organic molecules.
They have not been modified due to melting or other disturbances. They are formed when various types of dust and small grains that were present in the early solar system accreted to form primitive asteroids. They are the most common type of meteorite that falls to Earth: they are about 85 or 86 per cent of all meteorites.[2]
Their study gives clues about the origin and age of the Solar System, the synthesis of organic compounds, the origin of life or the presence of water on Earth. Chondrites can be differentiated from iron meteorites by their low iron and nickel content.
Achondrites
About 8 percent of meteorites show signs of melting and recrystallising. They look rather like basalt or granite.
Iron meteorites
Iron meteorites are meteorites made of an iron–nickel alloy. They are about 6 per cent of all meteorites. This comes from the inner cores of early small proto-planets.[3] The iron found in iron meteorites was one of the earliest sources of usable iron, before humans invented smelting. That signalled the beginning of the iron age. Iron meteorites are easily found, because native iron is rare.
Siderolites
Siderolites are stony-iron meteorites that have almost equal parts of iron and silicates. They are quite rare: only about 1 per cent of all meteorites are siderolites.
Related pages
References
- ↑ The use of the term non-metallic does not imply the total absence of metals.
- ↑ Bischoff, A.; Geiger, T. (1995). "Meteorites for the Sahara: find locations, shock classification, degree of weathering and pairing". Meteoritics 30 (1): 113–122. doi:10.1111/j.1945-5100.1995.tb01219.x. ISSN 0026-1114.
- ↑ Template:Cite book
The Solar System
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Image:Solar System Template Final.png
rect 0 0 90 35 The Sun
circle 112 18 6 Mercury
circle 153 18 8 Venus
circle 203 8 4 The Moon circle 194 18 8 Earth
circle 233 18 8 Mars circle 239 13 3 Phobos and Deimos
circle 271 18 8 Ceres rect 256 0 288 35 The main asteroid belt
circle 317 18 15 Jupiter circle 329 5 6 Moons of Jupiter rect 298 15 335 20 Rings of Jupiter
circle 372 18 12 Saturn circle 381 7 6 Moons of Saturn rect 353 5 389 31 Rings of Saturn
circle 418 18 12 Uranus circle 427 10 6 Moons of Uranus rect 408 4 429 34 Rings of Uranus
circle 462 18 12 Neptune circle 471 10 3 Moons of Neptune rect 441 9 485 28 Rings of Neptune
circle 504 18 8 Pluto circle 508 13 3 Moons of Pluto
circle 534 18 8 Haumea circle 538 13 3 Moons of Haumea
circle 567 18 8 Makemake rect 490 0 580 35 The Kuiper Belt
circle 596 18 8 Eris circle 600 14 3 Dysnomia rect 581 0 610 35 The Scattered Disc rect 623 0 640 35 The Hills Cloud rect 641 0 666 35 The Oort Cloud desc none
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| Sun • Heliosphere |
Planets ☾ = moon(s) ∅ = rings |
Mercury | Venus | Earth ☾ | Mars ☾ | ||
| Jupiter ☾ ∅ | Saturn ☾ ∅ | Uranus ☾ ∅ | Neptune ☾ ∅ | ||||
| Dwarf planets | Ceres | Pluto ☾ | Haumea ☾ | Makemake | |||
| Eris ☾ | |||||||
| Small Solar System bodies |
Asteroids (minor planets) |
Groups and families: Vulcanoids · Near-Earth asteroids · Asteroid belt Jupiter Trojans · Centaurs · Neptune Trojans · Asteroid moons · Meteoroids · Pallas · Juno · Vesta · Hygiea · Interamnia · Europa | |||||
| See also the list of asteroids. | |||||||
| Trans- Neptunians |
Kuiper belt – Plutinos: Orcus · Ixion – Cubewanos: Varuna · Quaoar · Huya | ||||||
| Scattered disc: Sedna | |||||||
| Comets | Periodic comets and non-periodic comets Damocloids · Oort cloud | ||||||
| See also the list of solar system objects | |||||||
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