Roth Planetarium Explorations
in Observation and Discovery
(A work in progress.)
For Grades 3rd - 12th Grades
Dr. James L. Regas
Director of the Roth Planetarium
Here is the actual core program that will be presented
to your class.
This is the basic program outline that the
Roth Planetarium Interns follow.
Put most simply, Astronomy is the Study of
light, gravity, and energy.
OBSERVING THE PLANETARIUM SKY -
Science begins with observation.Introduction - Star Topics
1. Why do stars shine? Why do planets and moons shine?
Stars - emit their own light because they are hot.
Planets shine by reflected light and circle stars.
Moons circle around planets and shine by reflected light
Galaxy - a large collection of stars.
Milky Way - galaxy the sun belongs to. The Milky Way galaxy contains 100 million stars. It is 80,000 light years across. The sun travels around the center of the galaxy in 200 million years.
2. Brightness: Are all stars same brightness? What determines the brightness of stars? Use light globe for brightness demo.
3. Size: Do stars look big or small? Why are stars so small - use string to show angles and Earth.
How big are stars. This is an ambiguous question.
Real vs. Apparent Size
Angular size is measured in degrees. Remember that there are 360° in a circle.
a. What happens to the angular size of the tennis ball as the ball is moved further away? ______________
b. Stars are big. Antares is over 100 million miles across. Why does it only look like a point of light in the sky? ________________
c. Can we estimate the size (in meters) of a UFO that we see in the sky? Can we estimate its speed in miles per hour?
4. Color: Are all stars same color? Use variac to demo why stars have different colors. What does the color of a star tell us about the star?
Spring: Use Aldebaran and Betelgeuse show orange stars.
5. Star clusters: Are the stars distributed uniformly across the sky or do they appear in groups? Groups of stars are called clusters.
Spring: Point out Pleiades and Hyades. Big Dipper is also in Ursa Major Open Cluster.
6. Space between stars:
Is the space between the stars uniformly dark.a. What do we call the bright band of light that runs across the sky?
b. What causes this bright band? (See Milky Way model.)
Show Milky Way Model. Galaxy 100 billion stars, 80,000 LY across.
THE MOTIONS OF STARS.
Staff: turn on the diurnal motion.
a. How are stars near the eastern horizon moving?
b. How are stars near the western horizon moving?
c. Locate the star Polaris (the north star). Is it moving?
d. How are the stars near Polaris, the north star, moving?
Demo: spin student on stool to show what moves stars.
Show Earth globe and how it moves and how the rotation axis points toward Polaris.
Circumpolar Concept: show stars go around Polaris and never set.
Circumpolar Constellations
A constellation is a pattern of stars in the sky. Astronomers use these patterns to help them learn where the stars are.
BIG DIPPER - CROSS ROADS OF THE SKY
Let’s look at two asterisms and two constellations: use can projectors.
Staff: show the asterism the Big Dipper and the constellation Ursa Major. Explain the difference to 7th grade and beyond. Point out the Pointers and Polaris.
Staff
: show the asterism the Little Dipper and the constellation Ursa Minor. Explain the difference. Point out the Guardians and explain how they guard Polaris.
Fall semester only: Asterism: summer triangle.
Ursa Major: use projector to show outline.
Big Dipper - How many stars are in the handle? How many in cup?
Mizar & Alcor double star.
Use balls to show how they line up.
If two stars are close together in the sky, does that mean that they are connected to each other like the Earth is connected to the sun?
Definition: An apparent binary star is two stars that are not close together in space but happen to fall in the same line of sight.
Definition: Real binary stars are two stars that orbit around each other like the Earth orbits around the sun. They are both at approximately the same distance from the Earth.
Staff: use two small balls to demonstrate apparent binary stars and real binary stars. Also use the auxiliary projector.
Then point out Mizar and Alcor.
2. How can we tell if two stars are gravity partners? What would we see them do over time?
Hint: If we watched the Earth from space, how could we tell that it was a gravity partner with the sun?
Staff: Use projector to show what Mizar A and B do.
Mizar is 59 light years away and Alcor is three light months further away.
Show Mizar binary star with auxiliary projector:
Notes on Mizar: Note Mizar A and Mizar B are both A stars. Mizar A is spectral class A2 V mag = 2.4, while Mizar B is a main sequence spectral class A7 p mag. 4.0. Both stars appear whitest.
The double star projector shows a blue and red star. This bears no relation to Mizar A & B.
Why doesn’t Mizar A fall into Mizar B?
Use ball to demonstrate spilling objects do not fall together.
Relate concept to solar system and Milky Way.
Delta cephei: point it out. Show how it pulsates with auxiliary projector. What are two possible explanations? Pulsation. Move toward and away.
Advanced Material for High School
THE NATURE OF LIGHT AND SPECTRA
Needed terms and concepts: Wave, diffraction, prism, diffraction grating, and spectra
Staff: Turn on the light bulb attached to the variac.
1. Students: Look at a light bulb through the space between your index finger and thumb. On the figure below draw what you see.
2. Now give a verbal description of what you saw.
a. color
b. shape
c. size
Definition: the bending of waves around the edge of an obstacle is called diffraction.
3. What does your simple finger-thumb observation tell you about the nature of light?
Prism, Light and spectra
Staff: pass the light from the slide projector through the glass prism.
1. What does the glass prism do to the light?
a. Where do you see this in nature?
How do astronomers know what stars are made of?
"The one thing that man will never know is the chemical composition of the stars."
Auguste Comte, French Philosopher
Staff: pass out diffraction gratings.
Diffraction gratings act like a prism and spread light out into a spectrum or a rainbow.
Observation #1: Staff turn on light bulb and have students look at it through the diffraction gratings. This kind of spectrum is called a continuous spectrum.
Observation #2: Staff turn on hydrogen emission spectrum and have students look at it through the diffraction gratings. This kind of spectrum is called an emission spectrum.
Observation #3: Staff turn on helium emission tube and have students look at it through the diffraction gratings.
Were the colors of the lines for hydrogen and helium the same or different?
Observation #4: Staff turn on unknown gas tube and have students look at it through the diffraction gratings.
Students: What is the gas in this tube? How do you know?
Reference material for core program:
Definition
: A constellation is a group of stars named by ancient astronomers.
Definition: An asterism is a group of stars which is inside a single constellation or a group of stars in several different constellations.
Definition: Mnemonics are formulas or aids to help in remembering.
Finding patterns: We will look for patterns in the stars to relate the known - usually letters or geometric shapes - to the unknown - patterns of stars.
Which pattern above would be easier for you to memorize #1 or #2?
Sign posts and paths in the sky: We will use certain asterisms as sign posts to direct us to stars and constellations.
2. Are all of the stars in a constellation at the same distance from the Earth?
Mizar actually consists of five stars. Mizar A and B are separated by 14". Mizar A has a magnitude of 2.4 and Mizar B has a magnitude of 4.0.
They were the first double star discovered with a telescope (Riccioli,1650), first to show a spectroscopic companion (Mizar A, P = 20.5 days, separation = 18 million miles, Pickering, 1898). Mizar B is also a spectroscopic binary, P = 182.3 days. Mizar B is an astrometric binary, P = 1,350 days. So the Mizar system has a grand total of 5 stars. The 3rd star you see in the field when you look at Mizar and Alcor through a small telescope is Sidus Ludovicianum, named after Ludwig V of Hesse-Darmstadt by a subject who mistook it for a new planet.. Sidus L. is also a spectroscopic binary L = 15 Lsun.
A (A0p), spec binary, sep = 0.19 AU B (A2 V), spec binary B, astrometric, P = 1,350 d
P = 20.5 d P = 182.3 d
Each have L = 35 Lsun
Each Mass = 3 Mass(sun)
** ** *
How to prove the Earth is rotating. For High school students. Foucault pendulum outside if possible, spin chair show keep same orientation.
