The Earth in Space

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The Earth in Space
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The Earths Gravity

• Gravity force of attraction between all matter.
• Law of Gravitation the force between two
  objects depends upon their masses and the
  distance between them

Isaac Newton
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• Are weight and mass the same?
• No!
• Mass the amount of matter in an object
• Weight strength of the pull of gravity
• Weight is measured in NEWTONS
• Weight depends on
• An objects mass and
• The objects distance from the Earths center

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• Knowing this, and that the Earths true shape is
  an oblate spheroid, where on Earth would you
  weigh the MOSTat the Poles or at the Equator?

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.3 more at the POLES
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Movements of the Earth

• A. Rotation the spinning of Earth on its axis
• This takes 24 hours

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B. Revolution

• Earths orbit around the sun.
• This takes 365.25 days
• Perihelion Earth is the closest to the sun
  (January 3rd)
• Aphelion Earth is the furthest AWAY from the
• sun (July 4th)

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• What causes Earths seasons?

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The Seasons

• 1. Summer Solstice first day of summer (in the
  Northern Hemisphere)!
• June 21st or 22nd
• Northern hemisphere is tilted TOWARDS the sun
• Suns rays are directly over the Tropic of Cancer
• 24 hours of sun at the Arctic Circle
• 24 hours of darkness at the Antarctic Circle

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• 2. Winter Solstice first day of winter (in the
  Northern Hemisphere)
• December 21st or 22nd
• Northern Hemisphere is tilted AWAY from the sun
• Suns rays are directly over Tropic of Capricorn

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• 3. Autumnal Equinox
• September 21st or 22nd
• Sun is directly over the Equator
• Equinox EQUAL day and night everywhere

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• 4. Vernal Equinox
• March 21st or 22nd
• Sun is directly over the Equator
• Equinox EQUAL day and night everywhere