Meteorites and Asteroids

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Meteorites and Asteroids

• Meteorites are pieces of asteroids that have
  fallen to earth. When asteroids collide in space,
  broken pieces will fly off in all directions.
  Some may eventually fly into the earths
  atmosphere where the heat generated will create a
  bright streak called a meteor. If the fragment
  reaches the earths surface, its called a
  meteorite.

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Canyon Diablo Meteorite

• About 50,000 years ago, a meteorite exploded in
  the Arizona desert, creating a crater nearly
  4,000 feet in diameter. The meteorite itself was
  only about 100 feet across, but it weighed 60,000
  tons and was traveling almost 45,000 miles per
  hour before it struck. The crater it formed is
  popularly known as meteor crater and is located
  near Winslow, Arizona. Meteorite fragments from
  this fall are called Canyon Diablo meteorites,
  named for the nearest city.

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Meteor (Barringer) Crater

• Nearly a mile wide and 570 feet deep

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When the impact occurred it produced an explosive
blast more than 1000 times more explosive than
the blasts which destroyed Hiroshima and Nagasaki
in World War II. Within three kilometers from the
impact, winds in excess of 2000 kilometers per
hour scoured the ground. Virtually any plant or
animal within that area was killed. The air blast
flattened trees out to distances of about 20
kilometers.
Effects of the Impact Event
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Widmanstatten Pattern

• The pattern you see here is of an etched slice of
  Gibeon IVA fine octrahedrite. This pattern is
  made up of two metals. The lighter bands are
  Kamacite and the darker bands are Taenite. These
  two alloys of nickel and iron crystallize at
  slightly different temperatures. So slightly that
  the cooling rate has to be about 1 degree per
  million years in order for this pattern to
  emerge. This could only happen in the molten core
  of a planet, and serves as proof that these
  objects could not have come from the earth.

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Sikhote-Alin Meteorite

• The largest shower in historical time occurred
  in eastern Siberia on February 12, 1947. In full
  daylight, a fireball moved from north to south
  and fragmented in the earth's atmosphere. The
  debris covered an elliptical area of 1.6 km on
  the snow-covered western spurs of the
  Sikhote-Alin mountains. The apparent diameter of
  the bolide with its luminous envelope was
  estimated to be 600 m. The brightness exceeded
  that of the sun. Altogether 122 impact holes were
  found with diameters ranging from 26 to 0.5 m and
  with depths ranging from 12 to 1 m. It appears
  plausible that the incoming bolide had a mass of
  about 70 tons. It split at an altitude of about 6
  km and scattered thousands of ragged fragments
  within an elliptical area. It is believed that
  many fragments were detached early in the flight
  and that these proceeded along with the main
  mass. The small area over which specimens are
  scattered suggests that the meteorite broke up
  very late in the atmosphere.

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Toluca Meteorite

• Xiquipilco (Jiquipilco), is the only place where
  people have forged their metal knives, spades,
  hammers, plows and other tools with iron from
  another world. Xiquipilco is a village situated
  700 feet above the Toluca valley and 25 km
  northeast of the city of Toluca -- the name
  commonly given to iron meteorites found in this
  area. The hillsides of Xiquipilco are etched with
  hundreds of small fields cultivated on the inner
  and outer slopes of long extinct volcanoes. Most
  of these small fields are so steep that the rows
  of corn and beans are like stair steps with the
  incline often steeper than many staircases. Over
  the years, rainfall has continually eroded these
  slopes exposing meteorites that have been the
  sole source of "native iron" to the haciendas of
  Xiquipilco and vicinity. With up to 14 tons of
  meteoritic iron recovered, it is comparable to
  the Magura, Sikhote-Alin, and Gibeon falls.
  Toluca is a polycrystalline, inclusion-rich,
  coarse octahedrite (group IA).