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How does the shape of the Earth affect our view
of the stars?
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We will be taking a virtual field trip to
different spots on the Earth and viewing the
stars there.
We are going to focus in on two major
constellations, and one very important
starPolaris, or the North Star.
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Through the magic of virtual astro-vision, we
will be viewing the sky at the same time in every
location we go to!
We need to do this so that we can see the sky the
same way at each location.
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As you may already know, our view of the
constellations change over an eveningthe stars
appear to move because the Earth is rotating!
Your view of the sky at 900 p.m. is different
from your view at 1100 p.m., just for example.
Polaris is the exception to this!!!
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We are going to deal with this problem by
arriving at each location at precisely the same
timethrough our superstellar supersonic time
machine (SSTM)!
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Hop on board!
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Hop on board!
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Hop on board!
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Hop on board!
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Hop on board!
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Our first stop is really closeby!
Central Park in New York City!
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What is the latitude of NY city?
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New York, New York 41o N Latitude
Big Dipper
Cassiopeia
Polaris
Pointer Stars
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We are going to calibrate our screen so that we
can make measurements of the location of Polaris
in other places on Earth.
We will be using a device called a sextant.
This measures the stars angle above the horizon.
This is called ALTITUDE.
This simulation is only in 2-D, so the sextant
appears like a ruler. However, in the real-world
of 3-D, this device would measure what angle you
have to tilt your head up in order to see a star.
Therefore, if the star is at the horizon, the
angle is ZERO. Directly overhead, the angle is
90o.
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New York, New York 41o N
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Big Dipper
Cassiopeia
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Polaris
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30
Pointer Stars
Measure the altitude of Polaris
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0
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What does this view feel like in 3-dimensions?
POLARIS
The arc represents the Celestial
hemisphere (the sky above)
E
41o
HORIZON
N
S
W
The ground
There is a 41 degree angle between the horizon
and Polaris.
In other words, the viewer must tilt his or her
head (and telescope!) up 41o from the horizontal
in order to directly see Polaris.
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Now lets head to Tampa, Florida and view the
night sky there!
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Tampa, Florida
What is the altitude of Polaris in Tampa?
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40
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0
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What is the altitude of Polaris in Tampa?
Again, lets get a feeling of what this looks
like in 3-D!
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What does this view feel like in 3-dimensions?
Plot the position of Polaris for Tampa
The arc represents the Celestial
hemisphere (the sky above)
E
HORIZON
N
S
W
The ground
In Tampa, would you tilt your head up more or
less than in New York in order to see Polaris?
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Tampa, Florida
Did you notice that the Big Dipper, and
Cassiopeia are also lower in the sky here
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New York, New York 41o N
than in New York!
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What is the latitude of Tampa?
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Now we are flying off to Popayán, Colombia in
order to view the tropical night sky!
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Popayán, Colombia
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What is the altitude of Polaris in Popayán?
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40
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10
0
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What is the altitude of Polaris in Popayán ?
Again, lets get a feeling of what this looks
like in 3-D!
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What does this view feel like in 3-dimensions?
Plot the position of Polaris for Popayán
The arc represents the Celestial
hemisphere (the sky above)
E
HORIZON
N
S
W
The ground
In Popayán, how would you have to orient your
head so you could see Polaris?
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What is the latitude of Popayán?
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Predict where you would find Polaris if you were
at the Equator (Oo)
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Lets see if you are getting the hang of this!
For our next stop we are going to view the sky
FIRST, and then predict our latitude from our
view of Polaris!
Pretty neat, huh!
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Mystery Location
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Before, we measure, determine this Are we North
or South of NY?
Here is NY again for comparison
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New York, New York 41o N Latitude
And now back to our mystery location!
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O.K.! Lets determine the altitude of Polaris
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So where is Polaris in this location?
The arc represents the Celestial
hemisphere (the sky above)
E
HORIZON
N
S
W
The ground
So now we know what latitude we are at. What is
it?
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Of the choices given, where in the world are we?
Churchill, Canada
Quebec, Canada
Hartford, CT
Washington, D.C.
New Orleans, LA
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Now that youre so good at this, predict the
altitude of Polaris at the North Pole!
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Lets imagine what it would be like to do this at
the North Pole. Be careful you dont strain
your neck!
and make sure you are EXTRA good while you are
here!!!! You know whos watching.
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80
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80
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90
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90
80
70
60
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What is the altitude of Polaris?
90
80
70
60
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Where is Polaris at the North Pole?
The arc represents the Celestial
hemisphere (the sky above)
E
HORIZON
N
S
W
The ground
Describe what you would have to do in order to
view Polaris at the North Pole.
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All aboard for our last stop! Another mystery
location for you to solve!
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To give you a hint, well place a marker where
Polaris would be if we were in New York at this
time
Do the measurement
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60
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0
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Of the choices given, where in the world are we?
Churchill, Canada
Ottawa, Canada
Philadelphia, PA
Meridian, MS
Havana, Cuba
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Well, our adventuring is over for today! Thanks
for making our mission a success!
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Well, our adventuring is over for today! Thanks
for making our mission a success!
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Well, our adventuring is over for today! Thanks
for making our mission a success!
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Well, our adventuring is over for today! Thanks
for making our mission a success!
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Well, our adventuring is over for today! Thanks
for making our mission a success!
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WHEE! See you next time!!!!!
Well, our adventuring is over for today! Thanks
for making our mission a success!