Transcript L#5: PowerPoint for Polaris Lab

How does the altitude of Polaris
change?
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
star—Polaris, or the North Star.
Through the magic of “virtual astrovision,” 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.
As you may already know, our view of
the constellations change over an
evening—the stars appear to move
because the Earth is rotating!****
Your view of the sky at 9:00 p.m.
is different from your view at
11:00 p.m., just for example.
****Polaris is the exception to this!!!
We are going to deal with this
problem by arriving at each
location at precisely the same
time…through our superstellar
supersonic time machine (SSTM)!
Hop on board!
Our first stop is really close by!
Central Park in New York City!
New York, New York 41o N Latitude
Big Dipper
Cassiopeia
Polaris
Pointer Stars
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 star’s 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.
70
New York, New York 41o N
60
Big Dipper
Cassiopeia
50
Polaris
40
30
Pointer Stars
Measure the altitude of
Polaris
20
10
0
What does this view “feel like” in 3-dimensions?
POLARIS
The arc represents the
Celestial hemisphere
(the sky above)
E
41o
HORIZON
N
S
The ground
W
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.
What is the
latitude of
NY city?
Now let’s head to Tampa, Florida and
view the night sky there!
70
What is the altitude
of Polaris in
Tampa? (Use the
pointer stars of the
Big Dipper)
Tampa, Florida
60
50
40
30
20
10
0
What is the altitude of Polaris in Tampa?
Again, let’s draw it in 3-D on the celestial sphere diagram!
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Did you notice that
the Big Dipper, and
Cassiopeia are also
lower in the sky
here…
Tampa, Florida
60
50
40
30
20
10
0
70
New York, New York 41o N
…than in
New York!
60
50
40
30
20
10
0
What is the
latitude of
Tampa?
Now we are flying off to
Popayán, Colombia in order to
view the tropical night sky!
70
Popayán, Colombia
What is the altitude
of Polaris in
Popayán?
60
50
40
30
20
10
0
What is the altitude of Polaris in Popayán ?
Again, let’s get a feeling of what this looks like in 3-D!
What is the
latitude of
Popayán?
Predict where you would
find Polaris if you were at
the Equator (Oo)
Let’s 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!
Mystery Location
Before, we measure,
determine this: Are
we North or South
of NY?
Here is NY again
for comparison…
New York, New York 41o N Latitude
And now back
to our mystery
location!
O.K.!
Let’s determine the
altitude of Polaris…
70
60
50
40
30
20
10
0
So where is Polaris in this location?
The arc represents the
Celestial hemisphere
(the sky above)
E
HORIZON
N
S
W
So now we know what latitude we are at. What is it?
The ground
Of the
choices
given,
where in
the world
are we?
Churchill, Canada
Quebec City,
Canada
Hartford, CT
Washington,
D.C.
New Orleans, LA
Now that you’re so good at this,
predict the altitude of Polaris at the
North Pole!
Let’s imagine what it would be like
to do this at the North Pole.
Be careful you don’t strain your
neck!
…and make sure you are EXTRA good while you are
here!!!! You know who’s watching….
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70
60
50
40
30
20
10
80
70
60
50
40
30
20
90
80
70
60
50
40
90
80
70
60
What is the altitude
of Polaris?
90
80
70
60
All aboard for our last stop!
Another mystery location for you to
solve!
To give you a hint, we’ll place a marker where Polaris would be
if we were in New York at this time…
Do the
measurement…
60
50
40
30
20
10
0
Of the
choices
given,
where
in the
world
are we?
Churchill,
Canada
Ottawa, Canada
Philadelphia,
PA
Meridian, MS
Havana,
Cuba
Well, our adventuring is over for today! Thanks for
making our mission a success!
Well, our adventuring is over for today! Thanks for
making our mission a success!
Well, our adventuring is over for today! Thanks for
making our mission a success!
Well, our adventuring is over for today! Thanks for
making our mission a success!
Well, our adventuring is over for today! Thanks for
making our mission a success!
Well, our adventuring is over for today! Thanks for
making our mission a success!
Question #2 from the June 2006 Regents