Requirement #4C

Make two sketches of the big dipper, In one sketch, show the Big Dipper's orientation in the early evening sky. In another sketch show its position several hours later. In both sketches show the north star and the horizon. Record the date and time each sketch was made.

We’re going to use the Stellarium program to run a night sky simulation…

Set up:

1. Start the Stellarium program.

2. Press the Ctrl-Q keys to turn on the N,S,E,W direction displays.

3. Press the Ctrl-V keys to display the Constellation names

4. Set the time to one hour after sunset.

o Bring up the Configuration Window and select the Date-Time Tab.

o Set the mouse cursor over the small up-down arrows near the Hour field.

o Adjust the time so the sun sets, the sky is dark and the stars show.

o Close the Configuration Window by clicking on the small box in the upper right hand of the Configuration Window.

5. Find North.

o Using the arrow keys on the keyboard, (note: the arrows that are part of the numeric keypad do not work for this), scroll the sky left or right until you are facing north. The letter 'N' should be displayed on the screen.

o Zoom out to see more of the sky by pressing the PageDown Key on the keyboard (remember the keys that are part of the numeric keypad don't work).

o Press the up arrow key so you are looking higher in the sky. Adjust it so the horizon is near the bottom of the screen.

Observation:

1. Find the constellation Ursa Major.
• The Latin word 'Ursa' means 'bear' and the Latin word 'major' means 'big'. So this constellation is known as the Big Bear. Ursa Major is easy to find because it includes the star formation known as the Big Dipper.
• Once you've found the Big Dipper make a sketch of it showing its position relative to the horizon.
• Record the date and time displayed in the upper left hand corner of the screen.
• If you are still having a hard time finding the big bear press the ctrl-R keys and you will see the actual pictures of the constellations. Press the Ctrl-R key again to turn off the pictures.

2. Find the North Star

o See the two stars that make up the one end of the bowl of the dipper that is opposite the handle? If you draw a straight line through those two stars to the middle of the screen you'll see that they point to another star that is at the end of the handle of a little dipper. Yep, that's the Little Dipper or Ursa Minor ('Minor' is Latin for little so this is the Little Bear). And that star at the end of the handle of the Little Dipper is the 'North Star'. Astronomers also call this star Polaris.

o Move the mouse cursor over Polaris and click the left mouse button. There should now be a small circle around Polaris. You can verify that this is the right star by looking at the information displayed on the upper left hand corner of the screen.

o Now here's something really neat to do. Press the space bar once. The Program will center Polaris on the screen. We need to do this for the next part of our experiment.

3 . Time Lapse Astronomy

o Now we're going to do what astronomers love to do most, travel through time. In the upper left hand corner of the screen you can see the date and time displayed.

o If you press the ctrl-J keys you can speed up the clock. Press it a few times. You'll start to see the stars move across the screen as time speeds up.

o Let’s let a few hours go by then hit the ctrl-K keys to stop time.

o Where is the big dipper now? Draw the big dipper in its new position on your drawing. Record the date and time displayed in the upper left hand corner of the screen.

o Also what did you notice about the star, Polaris, while time was passing by? If you missed it hit the ctrl-J keys again to speed up time and watch.

o Place Polaris in the correct position on your drawing.

Conclusion:

The observation is complete and you have the sketches you need for requirement 4C. A little research into your Astronomy Merit Badge booklet will tell you why the stars move the way they do. Make sure you understand why in case you counselor asks you.