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Earth, Moon, and Sun

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Earth, Moon, and Sun Chapter 19 – PowerPoint PPT presentation

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Title: Earth, Moon, and Sun


1
Earth, Moon, and Sun
  • Chapter 19

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Voting Questions How many of you
  • would like to live where it is dark all the time?

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How many of you
  • would like to live where it is light all the
    time?

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How many of you
  • enjoy having four seasons?

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How many of you
  • would like to travel into space?

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How many of you
  • would like to go to the moon?

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How many of you
  • would like to live on Mars?

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How many of you
  • would like to live on Mars if it meant never
    returning to Earth and seeing your family and
    friends again?

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  • Ancient Egyptians were among the first people to
    study the stars.
  • The study of the moon, stars, and other objects
    in space is called Astronomy.
  • In past times people believed the Earth to be a
    the center of the Universe and everything
    revolved around us.

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  • The Earth rotates on its axis which is an
    imaginary line that runs through the North and
    South Poles.
  • This axis is tilted to 23.5 degrees (the tilt of
    the Earth on its axis changes from 24.5 degrees
    to 22.5 degrees on a 41,000 year time scale).
  • Earth spinning on its axis is called its rotation
    (this is how we have day and night).

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  • A point on the equator rotates at about 1,600
    kilometers per hour (most commercial jets dont
    move this fast).
  • As the Earth rotates eastward, the sun appears to
    move westward across the sky.
  • The side facing the sun is daytime and the side
    not facing the sun is night time (no kidding Mr.
    J we are not stupid). DEMO

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  • The Earth rotates on its axis about once every 24
    hours.
  • The Earth also revolves around the sun.
  • The movement of one object around another is
    called revolution.

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Harvard Question
  • When are we closer to the SUN?
  • Summer or Winter

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  • One complete circle around the sun is called an
    orbit.
  • As the Earth circles around the sun it is not a
    perfect circle. The orbit is elliptical (this
    changes over time).
  • The elliptical orbit of the Earth around the sun
    changes on a 100,000 year time scale.

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  • There are 365 days a year, but actually it takes
    the Earth 365.25 days to make one orbit around
    the sun.
  • So this is why we have leap year.
  • What would happen if we did not have leap year?

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Earth has seasons because its axis is tilted as
it moves around the sun.
  • The SOLSTICE occurs in December and June.
  • It is when the axis of the Earth is facing
    towards or away from the sun.
  • When this occurs the sun will be directly over
    head at 23.5 degrees north or 23.5 degrees south

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Halfway between the solstices, neither hemisphere
is tilted toward or away from the sun.
  • This is known as an EQUINOX which means equal
    night.
  • During the equinox the daytime and nightime are
    about the same.
  • Vernal equinox occurs around March 21st, and the
    autumnal equinox occurs around September 21st.

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Phases, Eclipses, and Tides
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Moons Facts
  • It takes the moon 27.3 days to revolve around the
    Earth.
  • The moon has an oval orbit around the Earth.
  • The moon rotates on its axis once every 27.3
    days.
  • A day and a year on the moon is the same.
  • The same side of the moon, the near side always
    faces the Earth. The far side of the moon
    always faces away from the Earth.

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Phases of the Moon
  • The phase of the moon you see depends on how much
    of the sunlit side of the moon faces Earth.

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Eclipses
  • When the moons shadow hit Earth or Earths
    shadow hits the moon, an eclipse occurs.
  • An eclipse occurs when an object in space comes
    between the sun and a third object, and casts a
    shadow on that object.
  • There are 2 types of eclipses
  • Solar
  • Lunar

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Solar Eclipse
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Lunar Eclipse
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Tides
  • What causes tides?
  • Tides are the daily rise and fall of Earths
    waters on its coastlines.
  • When the tide comes in the tide rises until the
    water on the beach reaches the highest point.
    This is called HIGH TIDE.
  • Then the tide will go out until it reaches the
    lowest part on the beach. This is called LOW
    TIDE.
  • Tides happen regularly.
  • Tides occur in all bodies of water, but they are
    most noticeable in the ocean and large lakes.

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Spring Tides
  • Twice a month the moon, Earth and sun are lined
    up (During the full and new moons).
  • Their combined gravitational pull produces the
    greatest range between the high and low tide,
    called a SPRING TIDE.

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Neap Tides
  • In between spring tides, at the first and third
    quarter of the moon, the sun and moon pull at
    right angles to each other.
  • This produces a NEAP TIDE, a tide with the least
    difference between low and high tide.
  • During a neap tide the sun pulls some of the
    water away from the bulge. This tends to even
    out the water level reducing the difference
    between high and low tides.

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Tides
  • Tides are caused by the interaction of the Earth
    , the moon, and the sun.
  • This occurs by the force of gravity.
  • Gravity is the force exerted by an object that
    pulls other objects toward it.
  • As the distance between objects increase gravity
    decreases.

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The Effect of the Moons Gravity
  • The moon pulls on the side closest to it more
    strongly than it pulls on the center of the
    Earth.
  • This creates a bulge of water, called a tidal
    bulge, on the side of the Earth facing the moon
    (Letter A).
  • The water at point C is pulled toward the moon
    less strongly than Earth is as a whole.
  • This water is left behind to form a second bulge.
  • So you have tidal bulges at A and C and along
    coastlines in these areas you have high tides and
    the areas between the bulges are experiencing low
    tide.

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A
D
B
C
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  • As the Earth rotates different places on the
    surface of the Earth pass through the areas of
    the tidal bulges and therefore experience the
    change in water levels.

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The Daily Tide Cycle
  • As the Earth rotates, once per day, people on or
    near the shore experience high and low tides as
    they pass through the tidal bulges.
  • In most areas high tide occurs about 12 hours and
    25 minutes apart in each location.
  • As the Earth rotates eastern parts of the US pass
    through the area of the tidal bulge before points
    farther west. Therefore high tide occurs later
    the farther west you go along a coastline.

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  • In some places there are 2 high tides and 2 low
    tides a day.
  • In other places, the range between the water
    level is less dramatic. One set of tides may be
    so minimal that there appears to be only one high
    tide and one low tide.
  • This is common along the coasts of Texas and
    Florida, due to the gradual slope of the ocean
    floor of the Gulf of Mexico.

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Factors that Affect Tide
  • High tide in California on a certain day is not
    necessarily the same height as the high tide in
    Oregon farther up the shore.
  • Landforms such as capes, peninsulas and islands
    interrupt the waters movements.

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Monthly Tide Cycle
  • The suns gravity affects the tides as well as the
    moon even though it is much farther away.
  • Sometimes the moon and sun pull together on the
    Earths waters and at other times, they pull in
    different directions.
  • Changes in the position of the Earth, moon, and
    Sun affect the height of the tides during a month.

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Monthly Tide Tables
  • Even with the many factors involved scientists
    are able to predict the tides accurately for
    various locations.

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Earths Moon
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The Moon
  • Ancient Greeks thought the moon was perfectly
    smooth.
  • It was not until 400 years ago that scientists
    were able to study the moon more closely.
  • In 1609 Galileo made his own telescope by putting
    two lenses together and observed the moon.

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  • Galileo observed features on the moon called
    craters, highlands and maria.
  • Craters are small round pits caused by impacts.

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  • Galileo inferred some areas on the moon were
    highlands or mountains.
  • The moon also had dark, flat areas, which Galileo
    called maria.
  • The latin word for sea.

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  • Galileo thought that the maria might be oceans on
    the moon.
  • The maria are actually low, dry areas that were
    flooded with molten material billions of years
    ago.

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Moon Landing July 20, 1969
  • Neil Armstrong landed on the moon
  • Thats one small step for man, one giant leap
    for mankind.
  • He meant to say, Thats one small step for a
    man..
  • http//batesmotel.8m.com/

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  • Astronauts brought back samples to Earth.
  • Later Astronauts could stay on the moon for days
    instead of hours.
  • On the first trip to the moon astronauts brought
    back to Earth 382 kg of rocks to study.
  • Much of what scientists know about the moon came
    from the detailed study of these rocks.
  • Scientists have determined that the moon has
    cooled almost completely, unlike the Earth.

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  • Apollo astronauts circled the moon and took
    pictures.
  • Astronauts realized the far side of the moon is
    rougher than the near side.
  • 1998 the Lunar Prospector mapped the entire moon
    from an altitude of only 100 km. The Lunar
    Prospector found evidence that there is frozen
    ice in the lunar soil near the poles.

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