Intro
- Meteoroid → enters atmosphere → meteor → hits ground → meteorite
- Every year a flux of at least 10⁷ kg of meteorites reaches the earth
Meteoroid types
Origin
- pieces of other planetary bodies like Mars, the asteroid Vesta and the Moon.
- others are the dust of comets or fragments of cometary nuclei. These are behind the meteor showers which occur when the earth crosses a cometary orbit.
- material left from the collisional and accretionary process that formed the rocky planets. Such collisions continue to occur in the asteroid belt generating meteoroids.
Material
- Iron - probably the first source of iron used by humans sometime before the regular iron age
- Stony Iron
- divided into chondrites which have “chondrules” and achondrites. Chondrules are crystalline material derived from molten silicate droplets.
- The shergottites and related Martian meteorites are typically classified as achondrites. “the shergottites have been reliably shown to contain aromatic and alkylaromatic hydrocarbons, phenol and benzonitrile.”
- Some are carbonaceous - contain organic material. Eg. Murchison.
- Stony
Origin of life and its building blocks
- Considered elsewhere.
Records from Hindu history
- Jehangir and British times: MT.