Solar Motion

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Solar Motion
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Label front flap

• MOTIONS OF THE EARTH
• -DAY NIGHT

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Solar Motion

• Essential Question- Bell Ringer
• Why does the earth have day night?

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• Do other planets have day night?

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Solar Motion

• The Earth is a sphere (ball shape). Because of
  this only half can be lit by the sun at any one
  time.

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Solar Motion

• The earth spins (rotates) on its axis.
• The earth rotates in a counter-clockwise (west to
  east) direction
• It takes 24 hours for the earth to make one
  complete spin

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Solar Motion

• The half that is facing the sun, has light (day)
• The half that is facing AWAY from the sun has NO
  light (night)
• Planets moons that rotate also have day and
  night

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Solar Motion

• Essential Question
• Why does the earth have seasons? Do other
  planets have seasons?

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Solar Motion

• Space objects are held in orbit by a force called
  gravity (pull). Because of the pull of gravity
  between the sun and the planets, the planets
  follow a curved path (orbit) around the sun,
  instead of traveling in a straight line out into
  space.

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Revolution

• The earth revolves (follows a path) around the
  sun.
• The path it follows is called an orbit.

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Revolution

• Distance from the sun ONLY affects
• How long it takes for the planet to make one
  complete trip around the sun (year)
• The farther away from the sun, the larger the
  orbit, the longer time it takes to make one
  complete trip around the sun
• Distance from sun does NOT affect temperature as
  long as we are in orbit

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Solar Motion
As the earth moves around the sun in its orbit,
the tilt of the axis stays the same.
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Solar Motion

• As the earth moves in its orbit around the sun,
  the position of Earth in its revolution causes
• Sometimes the northern axis is leaning toward the
  sun, sometimes away, sometimes in between

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Solar Motion

• Sometimes the northern axis is leaning away from
  the sun
• Sometimes the northern axis doesnt lean either
  away or toward the sun

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Solar Motion
If there was no tilt, the suns rays would not
hit the earths surface so differently. Note the
differences in the places that have day.
23 degree tilt to axis
No tilt to axis
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Solar Motion

• Because the earth is a sphere and the earths
  axis is tilted at about a 23 degree angle,
• the suns rays do not hit earths surface the
  same way if the northern axis is pointed toward
  the sun as it does when the northern axis is
  pointed away from the sun

Northern axis away from the sun
Northern axis toward the sun
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Solar Motion

• When the northern axis is leaning towards the
  sun, the northern hemisphere gets the most direct
  rays
• Because of the position of earth in its
  revolution, days are longer so the earth has more
  time to absorb energy from the sun so the days
  are hotter.

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Solar Motion

• When the northern axis is leaning away from the
  sun, the northern hemisphere gets the least
  direct rays
• Because of the position of earth in its
  revolution, days are shorter so the earth has
  less time to absorb energy from the sun so the
  days are cooler.

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Solar Motion

• The winter solstice is the shortest day longest
  night of the year. (December 21)
• At the opposite side of the orbit, is the summer
  solstice (the longest day and the shortest night
  of the year. June 21)

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Solar Motion

• At the positions in earths orbit where the hours
  of day night are equal, the northern axis is
  not leaning toward or away from the sun.
• These days are called equinoxes. The spring
  equinox is on March 21, the Fall equinox is on
  September 23

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Solar Motion

• The earth revolves in a counter-clockwise motion
  around the sun.
• The days get longer between December and June.
• The days get shorter between June and Dec.

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Solar Motion
Planets that have a slight tilt to their axis
will also have seasons
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Solar Motion

• Essential Question
• Why do the sun, moon, stars APPEAR to rise in
  the east and set in the west?

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Solar Motion

• The earth rotates around its action in a
  COUNTER-CLOCKWISE direction.
• This causes the sun, moon, stars to APPEAR to
  rise in the East and set in the West.
• The earth is actually the one moving

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Solar Motion

• In the summer, the sun makes a shorter shadow at
  noon than in winter.
• This is because the sun is lower in the sky.

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Solar Motion

• The suns path across the sky is called the
  ecliptic.
• The sun follows a different path in each season.

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Solar Motion

• In the Northern Hemisphere. the suns path is
  higher in the sky in the summer.
• The sun follows a lower path (closer to the
  horizon) in the sky in the winter.

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Solar Motion

• In the Spring Fall, the sun follows a path that
  is higher than in winter, but lower than in
  summer.

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Solar Motion
Winter
noon

• sunset

sunrise
Summer
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Solar Motion

• Stars also seem to rise in the East and set in
  the West

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Solar Motion

• Stars that are above the North Pole appear to
  rotate around the North Star
• This apparent motion is caused by the earths
  rotation

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Solar Motion

• An eclipse occurs when the sun, moon, earth
  line up.
• A solar eclipse occurs when the moon is between
  the sun earth and the moon casts a shadow on
  the earth (blocks out the sun)

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Solar Motion

• Total Solar Eclipse

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Solar Motion

• A lunar eclipse occurs when the Earth comes
  between the sun moon. The shadow of the earth
  covers part or all of the moon.

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