COMETS

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COMETS
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COMETS

• A comet is a small body of ice, rock, and cosmic
  dust loosely packed together
• Comets contain a nucleus, dust tail and an ion
  tail

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COMETS

• Referred to as DIRTY SNOWBALLS due to their
  composition
• Probably left over from the time when the planets
  formed

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COMETS
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COMETS

• Passes close to the sun, solar radiation heats
  the comet and gas and dust stream off in the form
  of a LONG TAIL
• TWO TYPES OF TAILS
• dust tail and an ion tail
• Center is the nucleus

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COMETS

• Elongated orbits
• Ion tail always POINTS AWAY from the sun ion
  tail is blown away by solar wind (made of ions)
• Dust tails dont always point away from the sun

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COMETS

• Scientists think that comets come from
• Oort Cloud, spherical region that surrounds the
  solar system
• When gravity of a passing planet/star disturbs
  part of the cloud, comets can be pulled toward
  the sun.
• Kuiper belt, which is the region outside the
  orbit of Neptune.

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ASTEROIDS
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ASTEROIDS

• Small, rocky bodies that revolve around the sun
• Irregular shapes
• Orbit in the ASTEROID BELT wide region between
  the orbits of Mars and Jupiter
• Thought to be material left over from the
  formation of the solar system

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Asteroid Belt
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Types of Asteroids

• Outermost region of asteroid belt - asteroids
  are dark reddish brown (may be rich in organic
  material)
• Asteroids dark gray surfaces rich in carbon
• Inner most region asteroids are light gray
  (stony or metallic composition)
• Examples Hektor, Ceres, Vesta

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Examples of Asteroids
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METEOROIDS

• Meteoroid - A small, rocky body that revolves
  around the sun probably pieces of asteroids
• Meteorite meteoroid that enters earths
  atmosphere and strikes the ground
• Meteor bright streak of light caused by a
  meteoroid/comet dust burning up in the atmosphere

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Meteor
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Meteors

• Meteor Shower- happen when Earth passes through
  the dusty debris that comets leave behind

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Types of Meteorites
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IMPACT CRATERS
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IMPACT CRATERS

• When an object in space collides with another
  object in space impact crater
• Planets/moons with no atmospheres have MORE
  IMPACT CRATERS
• Atmosphere acts as a shield smaller objects
  burn up

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Impact Craters

• Every few thousand years impacts may be powerful
  enough to cause a natural disaster
• Impact that is large enough to cause a global
  catastrophe are estimated to happen once every
  few hundred thousand years, on average

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TORINO SCALE

• System that allows scientists to rate the hazard
  level of an object moving toward Earth
• 0 small chance of hitting Earth
• 10 definitely will hit Earth

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