Meteoroids

Meteoroids

• 2.
   A meteoroidis a small rocky or metallic body travelling through space.  Meteoroids are significantly smaller than asteroids, and range in size from small grains to 1 meter-wide objects.  Most are fragments from comets or asteroids, while others are collision impact debris ejected from bodies such as the Moon or Mars.
• 3.
   The visiblestreak of light from space debris is the result of heat as it enters a planet's atmosphere, and the trail of glowing particles that it sheds in its wake is called a meteor, or colloquially a "shooting star" or "falling star". A series of many meteors appearing seconds or minutes apart, and appearing to originate from the same fixed point in the sky, is called a meteor shower.
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   When meteoroidsintersect with the Earth's atmosphere at night, they are likely to become visible as meteors.  If meteoroids survive the entry through the atmosphere and reach the Earth's surface, they are called meteorites.  Meteorites are transformed in structure and chemistry by the heat of entry and force of impact
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   A meteoror "shooting star" is the visible streak of light from a meteoroid or micrometeoroid, heated and glowing from entering the Earth's atmosphere, as it sheds glowing material in its wake.
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   Meteors typicallyoccur in the mesosphere at altitudes between 76 km to 100 km (46–62 miles.  The root word meteor comes from the Greek meteōros, meaning "suspended in the air".  Millions of meteors occur in the Earth's atmosphere daily.
• 7.
  The visible lightproduced by a meteor may take on various hues, depending on the chemical composition of the meteoroid, and the speed of its movement through the atmosphere. As layers of the meteoroid abrade and ionize, the color of the light emitted may change according to the layering of minerals. Possible colors (and elements producing them) include:  • Orange/yellow (sodium)  • Yellow (iron)  • Blue/green (copper)  • Purple (potassium)  • Red (silicate)