Teacher’s Guide for:
OBJECTIVES:
·
To show how gravity can shape a star
·
To introduce the usefulness of the H-R Diagram to astronomers
·
To see how the spectrum of a star can tell us many things about
the star, including temperature
·
To investigate gravity and how we can achieve orbits
This show conforms to the following state science
standards:
BRIEF SHOW
DESCRIPTION:
“The StarGazer” depicts the journey of University of
Illinois scientist James B. Kaler on the road to becoming an astronomer.
Though the show is not a biography, we see how Dr. Kaler first became
interested in observing the sky, follow him through his decision to become an
astronomer, and finally see him as a teacher at the University of Illinois.
The show captures Dr. Kaler’s passion for the night sky.
We also look at gravity and how it shapes a star, go through how stars
are classified by their brightness and temperature, and introduce the
Hertzsprung-Russell Diagram, a vital tool in studying the stars.
Nichelle Nichols (Lt. Uhura from television’s Star
Trek) and Dr. Kaler himself narrate.
PRE-VISIT
ACTIVITIES/TOPICS FOR DISCUSSION:
·
Can money buy
happiness? Probably not, but how many of your students would like to
have, say, a million dollars? Make a graph on the board showing
happiness going up the vertical axis (from not very happy to very happy) and
wealth on the horizontal axis going from wealthy to poor. Most
people would fall along a line running from the upper left to the lower
right. What about the people in the upper right hand corner?
How about the lower left corner? Describe them. Does wealth
"cause" happiness or are the two just generally related? The show will do something similar relating
a star's brightness or luminosity to it's temperature. This is called the
“H-R Diagram,” named for two astronomers, Hertzsprung and Russell.
·
Discuss the idea of gravity and “escape velocity.”
Throw a tennis ball horizontally in the classroom but ask the students to
predict what will happen to it. This
is actually done in the show. Of
course it will fall. What if you
threw it harder (faster)? It
will go farther but it will still fall due to gravity.
If you could throw the ball 13,500 miles per hour, it would still fall
due to gravity pulling it towards the surface of the Earth, but now it’s going
so fast that the Earth’s surface curves beneath it, so the ball curves around
the Earth. You have an orbit! If you could throw the ball 25,000 mph, it would curve
a bit, but leave the Earth. You
have reached escape velocity! The
larger and more massive the planet, the larger the escape velocity. Raid the library and find what the escape velocity
would be for the Moon. How about
Jupiter? Pluto?
Mars? Would you need a
larger or smaller rocket to launch things off the surface of Mars?
·
Ask the class to brainstorm answers to this question:
How can we find out anything about the stars since we cannot visit them?
The most common answers will most likely include “use a telescope” or
“space probes.” Even in
powerful telescopes most stars are still small pinpoints of light and, although
we do have satellites monitoring the Sun, the space probes that have left the
solar system won’t reach the stars for thousands of years.
[Answer: analyze the
starlight!]
POST-VISIT
ACTIVITIES/TOPICS FOR DISCUSSION:
·
Research the origin of the spectral classes:
O B A F G K M. Can you think of a sentence that would allow you to
remember the letters in order easily?
Who was Annie Jump Cannon?
·
Observe some of the emission and absorption lines discussed in the
show by obtaining some inexpensive diffraction grating material (the Staerkel
Planetarium sells “Spectrum glasses” for $1 each) and have the students
observe several light sources in a darkened room.
Use a light bulb (preferably unfrosted) and maybe a neon light.
You can order discharge tubes for various gases such as hydrogen and
helium, but you’ll need a special transformer for this.
Even a mercury vapor streetlight works.
The Tungsten light bulb will give you a continuous spectrum or rainbow.
What about the neon sign or mercury vapor light?
Compare and contrast the different spectra.
If you were given an unknown tube of gas, how could you determine what
gas was contained inside if it was unlabeled?
·
Absorption spectra are not easy to observe and inexpensive
diffraction gratings won’t produce great results.
Project STAR (http://www.starlab.org)
sells kits to make a spectroscope that will show absorption lines (dark lines on
a continuous spectrum) if you point the instrument at the sky. Never point any instrument at the Sun! A blue, day time sky works nicely as you are really
looking at scattered sunlight.
·
Research the lives of the characters who appear in the show:
Galileo Galilei, Sir Isaac Newton, Cecilia Payne-Gaposchkin, and Albert
Einstein.
VOCABULARY LIST:
Spectra
Black Holes
Spectral Class
Giants
H-R Diagram
Spectroscope
Supergiants
Luminosity
INTERNET RESOURCES:
·
Visit Jim Kaler’s web sites at the University of Illinois:
http://www.astro.uiuc.edu/~kaler
·
More on buying a telescope: http://www.telescope.com.
or http://www.my-spot.com/whatkind.htm
or http://www.whyy.org/skytour/telescope.html
·
Close-up views of the Sun: http://sohowww.nascom.nasa.gov
or http://www.lmsal.com/TRACE/welcome.html
·
Fusion in the Sun: http://fusedweb.pppl.gov/CPEP/Chart.html
·
Star of the Week: http://www.astro.uiuc.edu/~kaler/sow/sow.html
·
Classifying stars: http://zebu.uoregon.edu/~imamura/208/jan18/mk.html
·
Find the Ring Nebula in the Messier catalog at http://www.seds.org/messier/
·
Hubble pictures: http://oposite.stsci.edu/pubinfo/pictures.html
·
Exploring Gravity activities: http://www.curtin.edu.au/curtin/dept/phys-sci/gravity/
·
Women in Astronomy http://www.aspsky.org/html/astro/womenast_bib.html
·
How to become an astronomer: http://www.aas.org/education
· More
on the H-R Diagram: http://ast.star.rl.ac.uk/hr.html
or http://zebu.uoregon.edu/~soper/Stars/hrdiagram.html
or a simulator at http://www.astro.ubc.ca/~scharein/a311/Sim/hr/HRdiagram.html
·
Astronomy Teaching tips: http://www.astro.wisc.edu/~kth/teaching/tips.html