Meteoroid
A meteoroid [ meteoroˈiːt ] (plural meteoroids or meteoroids ; analogy to asteroid and asteroid from meteor and ending -oid ) is a small object of the solar system on an orbit around the sun that is smaller than an asteroid.
A small percentage of the meteoroids cross the earth's orbit . When entering the high atmosphere , they become visible as shooting stars ; the brighter of these meteors are called fireballs .
properties
The size of meteoroids ranging from fractions of a millimeter (micrometeoroids) up to several meters, corresponding to a mass of milligrams to several tons , and have different backgrounds: You can by the gravity of the planet from the asteroid belt , but also by the solar wind from Comet nuclei have been detached, which lose them on their orbit and thereby disintegrate into a meteor shower. The term meteoroid current is more correct, but not common. Furthermore, they can also consist of material from asteroids, dwarf planets or planets due to impact or collision . So meteorites were found on earth , which probably come from Mars and the moon ( see: Martian meteorite , moon meteorite ). The vast majority of the meteorites found on earth come from asteroids.
For the aerospace meteoroids pose a risk, as because of its high speed, the impact energy is so high that even particles can result in less than one centimeter in size to considerable destruction.
Demarcation
- Meteoroids are larger than interplanetary dust and smaller than asteroids . There is no clear boundary between meteoroids and asteroids in terms of size or composition. Together with the asteroids and comets , meteoroids belong to the small bodies of the solar system.
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Meteors : If meteoroids enter the earth's atmosphere , they create a luminous phenomenon called a meteor through the recombination (not through friction) following the ionization of the air particles . The compression of air in front of the meteoroid creates a likewise ionized and brightly shining gas ball made of heated air and vaporized, initially solid matter . Small meteors are also known as falling stars , large ones as fireballs or bolides .
- Meteors that do not belong to a meteor shower are called sporadic meteors . Their traces of light in the starry sky follow a random distribution .
- Meteorites : A not completely burned up meteoroid or asteroid that reaches the surface of the earth is called a meteorite .
- Micrometeorites : smaller than about 1 mm, do not burn up, but slowly float to the ground as meteor dust .
literature
- Quarterly Journal of the Royal Astronomical Society: On the Definition of the Term Meteoroid, bibcode : 1995QJRAS..36..281B (English)
- Arnold Hanslmeier : Introduction to Astronomy and Astrophysics , Chapter 6.14 Meteoroids . Springer Spektrum Verlag, Berlin 2013
- Markus Landgraf: The nemesis of space travelers . In: Stars and Space . 6/2008. Pp. 36-43
Remarks
- ↑ Astrolexicon: What is a meteor? Retrieved January 20, 2009 .
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