Rotation

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Rotation Spin or Turn on an Axis
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Vertical Axis- Like the skater Horizontal Axis
like the log Rotational Axis like the Earth
Earths Axis is tilted 23.5 degrees from vertical
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What do you observe about the angle of the tilt?
They are all the same
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Earth's rotational axis points in the same
direction relative to the stars, so that the
North Pole points towards the star Polaris or
North Star
This constant allows sailors to navigate at night
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The Earth Continuously Rotates on its Axis
causing Day and Night
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• The Earth
• Rotates around once in 24 hours
• Time to rotate completely around
• once is called a day

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The Earth Continuously Orbits the Sun or Revolves
The time it takes for the Earth to go completely
around the Sun is called a year.
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Like all planets in our
solar system, the Earth is in an
elliptical orbit around our
Sun. In Earth's case, its orbit is
nearly circular, so that the difference between
Earth's farthest point from the Sun and its
closest point is very small.
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It takes 365.25 rotations for the Earth to go
around the Sun once.
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Each 4 years, one day is added to the month of
February to make up for the 0.25 (1/4) rotation
in each revolution around the sun.
February 29
This is called Leap Year
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If you are born on February 29, when do you have
a birthday?
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The Earth moves in definite pattern around the Sun
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The tilt of Earths rotational axis and the
Earths orbit work together to create the seasons.
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When the northern hemisphere is tilted towards
the sun, the southern hemisphere is tilted away.
This is why the hemispheres have opposite
seasons.
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Sometimes the Earths axis is pointing toward
the Sun and other times the Earths axis is
pointing away from the sun.
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Halfway in between the solstices, the Earth is
neither tilted directly towards nor directly away
from the sun
These points are called equinoxes. Both
hemispheres receive about equal amounts of
sunlight.
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Equinoxes mark the seasons autumn
(fall) and spring and are a transition between
summer and winter
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Lets Review
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What is the turning of an object around its axis
called?
AXIS
A revolving B rotating C rolling D ballet
dancing
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What is the science term for the turning of an
object around its axis called?
B rotating Correct Rotating is the turning or
spinning around an axis
A revolving Incorrect Revolving is moving
around another object
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What is the science term for the turning of an
object around its axis called?
C rolling Incorrect Act of causing an object to
turn or rotate
D dancing Incorrect Many dance step do not
require the rotation of the dancers body
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How long does it take the Earth to make one
rotation?
-Correct- It takes 1 day or 24 hours
A day B week C month D year
-Incorrect A week is 7 days
-Incorrect It takes about a month for
the moon to rotate
-Incorrect It takes 365.25 rotations
for a year
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The constant pattern of the Earths orbit and its
tilt causes spring to always come before what
season?
-Incorrect it comes before winter
A autumn B winter C summer
-Incorrect it comes before spring
-Correct spring is
the transition from winter to summer
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What season is it in the southern hemisphere
when it is winter in the northern hemisphere?
A spring B summer C autumn
-Incorrect spring is the opposite season to
fall
-Correct- the south pole is
tilted toward the sun

• Incorrect autumn is
• opposite to the spring season

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The following are constant except for
-Incorrect The
earth rotates continually causing day/night
A Earths Rotation B Earths Orbit C order of
seasons D weather
-Incorrect The
earth orbits in the same path yearly
- Incorrect The
season are caused by tilt and orbit of the earth
- Correct Weather changes
continually.
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What does the Earth revolve around?
A moon B Milky Way Galaxy C Nothing D sun
Incorrect The moon revolves around the Earth
-Incorrect The Earth is part of
the Solar System
-Incorrect- Observation has shown this incorrect
(Everything revolves around the Earth)
Correct All planets and planetary systems in
the Solar System revolve around the sun
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During 2006, which of the following will remain
constant in Texas?
Incorrect weather may change by the
minute
A weather B same stars seen every night C tilt
of Earths axis D temperature

Incorrect Some stars are only
seen during certain months
Correct
The axis will be tilted
at 23.5 degrees all year
Incorrect-
Temperature changes
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Information and graphic sources
Microsoft Office Online
http//kids.msfc.nasa.gov/Earth/Seasons/Seasons.ht
m
http//www.windows.ucar.edu/tour/link/image_linki
ng.html
http//www.windows.ucar.edu/tour/link/the_univers
e/uts/earth2.html
http//www.classzone.com/books/earth_science/terc/
content/visualizations/es0408/es0408page01.cfm?cha
pter_no04