CIM R13

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CIM R13
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• A glance at the surface of the moon shows that
  meteor impacts in our part of the solar system
  are pretty common. The Earth itself is not
  covered with craters because most meteors burn up
  in the Earths atmosphere and because geological
  processes have destroyed the evidence of pas
  impacts. Here and there on the surface of the
  Earth, giant craters can non-the-less be seen.
  One example is the large impact crater near
  Winslow, Arizona, which measures about 1.2
  kilometers across

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• As the Arizona crater demonstrates, the Earth is
  sometimes hit by large meteors. In 1908, for
  example, a meteor 50 meters in diameter exploded
  above the ground in the Tunguska region of
  Siberia and knocked down trees over an area of
  2,000 square kilometers. According to
  scientists, a meteor of that size strides the
  Earth, on average, once every three hundred
  years.
• The Tunguska meteor was not the largest one that
  has ever hit the Earth. At the end of the
  Cretaceous Period, about 65 million years ago,
  most of the life on Earth, the dinosaurs
  included, was destroyed when a meteor 10
  kilometers in diameter hit the Yucatan peninsula
  in Mexico. The impact threw enough debris into
  the air to block the sunlight for many months and
  to kill most of the

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• plants and animals.
• Fortunately for us, the larger outer planets of
  the solar system, Saturn and Jupiter, provide
  some protection against meteors. The gravity of
  a large planet like Jupiter or Saturn acts like
  an enormous slingshot, throwing large meteors
  that enter the solar system back out again so
  that they do not hit the Earth. If not for these
  large planets, the earth would be hit by large
  meteors quite often, and life on our planet wound
  not exist.

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6. The Earth is not covered with meteorite
craters because

• A. Meteor impacts in our area of the solar
  system are very rare
• B. Over time the action of geological forces has
  destroyed the evidence of past impacts
• C. Impacts occur only in a very limited area of
  the Earths surface
• D. Most meteors that enter the Earths
  atmosphere go into orbit around the Earth

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7. Scientists estimate that the diameter of the
Yucatan meteor was

• A. 1.2 kilometers
• B. 50 meters
• C. 10 kilometers
• D. 2,000 kilometers

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8. When did the Tunguska meteor impact occur?

• A. About 65 million years ago
• B. About three hundred years ago
• C. In 1908
• D. Cannot be determined

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9. All of the following occurred as a result of
the meteor impact in the Yucatan EXCEPT

• A. Debris from the impact blocked sunlight for
  many months.
• B. Most of the plant life on Earth was
  destroyed.
• C. New species of dinosaurs evolved as a result
  of mutations brought about by the impact.
• D. Most of the animals on Earth died.

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10. What helps prevent meteors from crashing
into Earth?

• A. An electromagnetic field around the Earth
  blocks most meteors from entering the atmosphere.
• B. The gravity of Jupiter and Saturn acts like a
  giant slingshot, throwing large meteors back out
  of the solar system.
• C. The gravity of the sun attracts meteors away
  from the Earth.
• D. The moon attracts meteors, keeping them from
  hitting the Earth.

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