Planets

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Planets Motions in Space
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• The planets in the solar system orbit our sun in
  a specific arrangement.
• 500 years ago no one even knew that they even
  went around the sun.
• One guy, Johannes Kepler, spent 20 years studying
  the planets orbits.
• He came up with his 3 laws of planetary
  motionvery smart.

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• Johannes Kepler
• Nowait
• Thats better
• Pretty good looking, huh, girls?

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Keplers Laws of Planetary Motion

• 1. The path of a planet around the sun is an
  ellipse.
• The orbits are not circular and the sun is not at
  the center of the ellipse.
• So, sometimes the earth is closer to the sun and
  sometimes it is farther away.
• Planets move faster when closer to the sun and
  slower when farther away.

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1. As planets move around the sun, they sweep out
   equal areas in equal times

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• 3. The time to go around the sun (orbit) is
  proportional to the distance from the sun.
• - closer planets take less time to orbit the
  sun.
• - closer ones also move faster.
• AUAstronomical Unit150 million kmaverage
  distance from Earth to Sun

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• Mercury (closest to sun) orbits in 88 days,
  while Pluto (farthest) orbits in 247 years!