Earth, Moon, and Sun

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Earth, Moon, and Sun
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Earth
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Properties of Earth

• Earth is a sphere
• - As early as 350BC astronomers thought
  the Earth could be round
• - They saw shadows during eclipses and
  ships on the horizon

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Properties of Earth

• - Sailors were often also astronomers
• - The study of the moon, stars and
  other objects in space is astronomy

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Properties of Earth

• - They saw that the stars changed
  heights in the sky depending on how far
  north or south they sailed

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Properties of Earth

• - The Earth is not a perfect sphere
• - It bulges at the equator and
  flattens at the poles
• - This is because of gravity and rotation

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Properties of Earth

• The Earth is rotating
• - Earth rotates around an imaginary line
  called an axis

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Properties of Earth

• - This is what causes night and day
• - One complete rotation takes 24 hours

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Properties of Earth

• The Earth is revolving
• - While the Earth is turning on its axis
  it is also orbiting the sun

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Properties of Earth

• - This orbit is called revolution
• - The earth takes 365 ¼ days to revolve
  around the sun

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Properties of Earth

• The Earth has a magnetic field
• - Because of rotation of Earth and
  convection within Earth a magnetic field is
  generated

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Properties of Earth

• - This creates a magnetic north and south
• - This magnetic field protects us from
  harmful solar radiation by trapping
  particles from the sun

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Properties of Earth

• - When particles from the sun interact
  with Earths magnetic field, a glowing
  display called an aurora can be seen in the
  sky

This was left out of the packet you will have
to write it in on your own in the top left margin!
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Properties of Earth

• - Magnetic north is found at an 11.5o angle
  to the rotational axis

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Properties of Earth

• - The magnetic field also produces lines
  of alternating charge in rock at
  mid-ocean ridges

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Seasons on Earth

• Orbiting the sun
• - Earths revolution around the sun
  places the planet at different distances
  from the sun at different times during the
  year

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Seasons on Earth

• - It is farthest from the sun around July 4
  and closest to the sun around January 3

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Seasons on Earth

• - This is caused by Earths elliptical
  orbit
• - An ellipse is an oval shape

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Seasons on Earth

• A tilted axis
• - Earths rotational axis is tilted 23.5o
• - This causes the seasons

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Seasons on Earth

• - Daylight hours are longer for the
  hemisphere that is titled toward the sun
  (summer) and shorter if tilted away (winter)

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Seasons on Earth

• - The hemisphere tilted toward the sun also
  receives more solar radiation

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