Teacher's Guide for:

Star Journey

OBJECTIVES:

• To examine the stars in the current night sky to see their similarities and differences.
• To see how Native American tribes viewed the night sky and it's origin.
• To investigate how the spectrum can provide us information about the stars.
• To discover how stars are born, live and eventually die. 

This show conforms to the following state science standards:  11.A.3f, 12.C.5a, 12.F.2b, 12.F.2c, 12.F.3c, 12.F.4a, 12.F.4b, 12.F.5a, 12.F.5b

What are the stars? What are they made of? Why are they different colors? What makes them shine? How are they born and how do they die? Though they are so far away that we see them as pinpoints of light even in the largest telescopes, we still have enough information about these distant beacons to offer good guesses to the answers to these questions. These questions and the spectrum are investigated during the course of Star Journey, a 50-minute live presentation offered by the Staerkel Planetarium for the grade 6-8 level.

1. List what we know about the stars. How do we know these things since we can't yet venture to see them up close?
2. How can we know how stars live and die if their lives last billions of years? Can we see them age?
3. What is a "light year?" How is it used to measure distances in the universe?

1. Fasten two paper plates together to model our galaxy, the Milky Way. Label the central nucleus, the spiral arms, and the position of our Sun, nearly 2/3 of the way from the center to the outer edge. Using this simple model, discuss how we see the Milky Way on clear, dark nights. From what perspective do we see our galaxy? 
2. Use a prism to divide the Sun's white light into the different colors of the spectrum. If you put a piece of red cellophane on the sunlight side of the prism, what effect does it have on the spectrum? Inexpensive diffraction gratings, which accomplish the same results as prisms, may be obtained for the class. With these you can observe emission lines from different sources. Start with the lights in the classroom and then obtain a hydrogen, helium, neon, or maybe a nitrogen discharge. You may use this to introduce the absorption and emission process. The star's high-pressure core will produce the full range of rainbow colors, but the cooler outer atmosphere of the star will produce absorption lines in the spectrum. 
3. It is interesting to note that all we know about the distant stars has come through two types of measurements: 
   a) a star's position, and b) a star's light output. 
   You may want to discuss how light is produced and methods of detection (e.g. the eye, photographic plates, charge-coupled devices), comparing the process to manmade sources of light (e.g.. a neon sign). 
4. Use different colored balloons to represent the different types of stars. Include red and blue giant stars, yellow sun-like stars, plus red and white dwarfs. In the following model, use a large marble about one inch in diameter (painted yellow, if you wish) to represent the Sun. You may then create the following stars to scale:

   Star	Color	Times Larger Than the Sun	Scale Diameter
   Betelgeuse	red	600	Hot air balloon
   Aldebaran	red	40	Beach Ball
   Arcturus	orange	25	.
   Capella	yellow	13	basketball
   Sirius	white	1.8	golf ball
   Sirius B	white	0.02	point of pin
   Spica	blue	8	.
   Rigel	blue	50	.
   Deneb	blue	60	.

5. The expansion of the universe may be demonstrated by inflating a balloon only about halfway. Use a marker to put dots randomly spaced on the surface of the balloon. These will represent galaxies. With the class observing, inflate the balloon further. The dots will move away from each other. Explain that the view from any one of the dots will show that the other galaxies are moving away. (Although the sizes of the dots increase in this demonstration, the galaxies do not expand as they separate from each other.) 
6. Show an old photograph to the class. This is an old photo of people when they were young. In similar way, we are seeing old starlight that has traveled over great distances in space, but, when we view distinct objects, we are seeing them as they were in a younger time. Secondly, in the snapshot, we see people of different ages. Can we make some guesses as to how people age? We must do the same thing with the stars since we are only seeing a "snapshot" in their long lifespans.

INTERNET RESOURCES:

Sky & Telescope Magazine:   http://SkyandTelescope.com
Astronomical Society of the Pacific:  http://www.astrosociety.org
For beginning amateur astronomers: http://www.calweb.com/~dmurry
CU Astronomical Society: http://www.prairienet.org/cuas
Stars & Constellations: http://www.astro.wisc.edu/~dolan/constellations/constellations.html
The latest Hubble images:  http://oposite.stsci.edu/pubinfo/latest.html
The SOHO mission to study the Sun:  http://sohowww.nascom.nasa.gov
Jim Kaler's "Skylights:"  http://www.astro.uiuc.edu/~kaler/skylights.html
Stellar spectra:  http://www.astro.uiuc.edu/~kaler/sow/spectra.html
Observing the "deep sky:"  http://Messier45.com/
Some thoughts on astrology:  http://www.badastronomy.com