METEORITES

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METEORITES
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Hey stars are falling ,I want to go and pick one
outside
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Whao! I cannot see anything on the ground outside
I have to ask Prof .
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Prof, I saw stars falling from the sky, I wanted
to pick them but I could not see them on the
ground
Ha! Ha! They are not stars but Shooting Stars
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What are Shooting Stars?
Hey! It is better we start from the
beginning
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THE SOLAR SYSTEM CONSISTS OF

• THE SUN
• THE EIGHT PLANETS
• MOONS
• ASTEROIDS
• COMETS
• DUST GAS

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• THE SUN A Huge ball of gas that gives out
  radiation as a result of thermonuclear reactions
  in its core. It is the sustainer of life on earth
  and balance in the solar system
• THE PLANETS Spherical objects that orbit a star
  and do not shine with their own light. Mercury,
  the smallest has diameter 2,440km

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Sources of Meteorites

• Asteroid an irregularly shaped rock that orbits
  the Sun, mostly occurring in a band asteroid belt
  between the orbits of Mars and Jupiter. Asteroids
  range in size from the largest, Ceres, with a
  diameter of 930 km/580 mi, down to dust particles
• Comet an astronomical object that is composed of
  a mass of ice and dust and has a long luminous
  tail produced by vaporization when its orbit
  passes close to the sun.

Comet Hale-Bopp
Asteroid Mathilde
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Comets The name "comet" comes from the Greek
meaning "long-haired" because of their tails. The
nucleus of a comet is like a ball of rock and
dirty snow. As these objects get close to the sun
the frozen gases and dust begin to heat and cause
a long tail of vaporized gases, dust and debris
to flow behind them. As it melts a cloud of gases
and dust forms a coma. The head of the comet is
the nucleus and coma together. Halley's Comet
appears about every 76 years.
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• Comets streaking across the sky have inspired
  dread, fear, and awe in many different cultures
  and societies around the world and throughout
  time. They have been branded with such titles as
  "the Harbinger of Doom" and "the Menace of the
  Universe."

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Origin of Comets
Comets originate from the Kuiper belt (short
period comets) and the Oort cloud (long period
comet).
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Asteroids originate in the Asteroid belt as shown
above
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ASTEROIDS

• Located in the Asteroid belt
• largest Ceres with 940 km diameter
• small fraction of the Solar System

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Types of Asteroids

• C-type
• carbonaceous(largely carbon, dark)
• 75 of the asteroids
• outer orbits
• very old (4.6 billion years)
• S-type
• silicate(largely silcon, light)
• 15 of the asteroids
• inner orbits
• M-type
• nickel-iron
• about 10 of the asteroids

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Earth and Mars Crossing Asteroids

• Apollo asteroids
• Earth crossing with semi-major axis greater than
  1 AU
• Aten asteroids
• Earth crossing with semi-major axis less than 1
  AU
• Amor asteroids
• Mars crossing
• all the Earth crossing asteroids will eventually
  collide with the Earth
• this occurs about 3 times every million years

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Meteor
Meteoroid
Meteoroid swarm
Bright streak in the sky caused by piece of
debris "shooting star"
Chunk of debris before entering Earth's atmosphere
Meteorite

• Fragments from comet that follow same orbit

A piece of a meteoroid that survives and lands on
Earth
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Shoemaker Levi9 Impact
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Shooting stars have always aroused interest world
wide and throughout the ages. People rush to
collect them either as souvenirs or as objects of
scientific study.
Shooting stars occur either when the earth passes
through the region of a comet tail or when a
meteorite explodes in the Earths atmosphere,
scattering fragments which fall as meteorites.
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Finds
Tagish lake meteorite

• Generally, people do not see meteorites falling,
  but they recover them as finds. Most are
  relatively small

Meteorite find at Arizona,USA
Meteorite find at Timbuctu Mali
Meteorite find at Oman
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An asteroid strike is believed to have caused the
mass extinctions of the dinosaurs 65 million
years ago, could it happen again?
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IMPACT CRATERS
Manicouagan Crater in Canada as seen from a
satellite
Bosumtwi crater lake, Ghana

• When a large object impacts the surface of the
  Earth, the rock at the site of the impact is
  deformed and some of it is ejected into the
  atmosphere to eventually fall back to the
  surface.  This results in a bowl shaped
  depression with a raised rim, called an Impact
  Crater.  The size of the impact crater depends on
  such factors as the size and velocity of the
  impacting object and the angle at which it
  strikes the surface of the Earth.

Barringer Meteor Crater - Arizona
Aerial view of Lake Pingualuk, Canada
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Tracking and Predicting Asteroid Encounters

• Recently some astronomers found some objects that
  were predicted to hit the Earth in 2028 and 2030.
  After further study both objects were projected
  to miss by several million miles. A system has
  been designed to avoid public panic and fear over
  an asteroid or comet hitting the Earth.
• The International Astronomical Union has a system
  to alert the public to such possible collisions
  by asteroids and comets. The Torino Scale as it
  is called is designed to rate the level of damage
  an object might do to the Earth if it hit. This
  method is similar to the Richter Scale used for
  earthquakes and scales used for severe weather
  and tornados.

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Do not panic, any other time you see a shooting
star, just explain what they are to your friends .
Thank you prof, you are the best
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• THANKS FOR YOUR ATTENTION!!!!!!!!!!!