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 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.

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 41 o 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. ALTITUDE 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 90 o.

New York, New York 41 o N Big Dipper Cassiopeia Polaris Pointer Stars Measure the altitude of Polaris

N S W E 41 o POLARIS HORIZON 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 41 o from the horizontal in order to directly see Polaris. What does this view “feel like” in 3-dimensions? The arc represents the Celestial hemisphere (the sky above) The ground

What is the latitude of NY city?

Now let’s head to Tampa, Florida and view the night sky there!

Tampa, Florida What is the altitude of Polaris in Tampa? (Use the pointer stars of the Big Dipper)

What is the altitude of Polaris in Tampa? Again, let’s draw it in 3-D on the celestial sphere diagram!

Tampa, Florida Did you notice that the Big Dipper, and Cassiopeia are also lower in the sky here…

New York, New York 41 o N …than in New York!

What is the latitude of Tampa?

Now we are flying off to Popayán, Colombia in order to view the tropical night sky!

Popayán, Colombia What is the altitude of Polaris in Popayán?

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 (O o )

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 41 o N Latitude And now back to our mystery location!

O.K.! Let’s determine the altitude of Polaris…

N S W E HORIZON So where is Polaris in this location? The arc represents the Celestial hemisphere (the sky above) The ground So now we know what latitude we are at. What is it?

Of the choices given, where in the world are we? New Orleans, LA Washington, D.C. Hartford, CT Quebec City, Canada Churchill, Canada

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….

What is the altitude of Polaris?

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…

Of the choices given, where in the world are we? Meridian, MS Havana, Cuba Philadelphia, PA Ottawa, Canada Churchill, Canada

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!

WHEE! See you next time!!!!!

Question #2 from the June 2006 Regents