1. Go over 3 homework questions

2. Answer Key
1. Draw a diagram showing what happens to white light when it passes through a prism.
2. Sketch and label the parts of a wave. How does wavelength vary with color?
Red light has longest
wavelengths. Blue or violet
light has the shortest.
3. Describe how Sir William Herschel showed that there are forms of radiation that we
cannot see with our eyes.
Herschel measured the temperatures of different wavelengths of sunlight. He spread
sunlight out into its component colors by passing it through a prism. He then put
thermometers in different colors of the spectrum and recorded their temperatures
over a few minutes. He found that the temperature was higher near the red end of the
spectrum than near the blue end. He also put a thermometer just beyond the red part
of the spectrum, where there was no visible light. He found that the temperature just
beyond the red was even higher than that near the red. Some kind of radiation that
we can’t see with our eyes was heating the third thermometer. Scientists now know it
was infrared radiation.
Credit: © Michael Guidry, University of Tennessee, Knoxville
Point out again that stars and other celestial objects are so far away from us that the only thing about them that astronomers can study is the energy that travels from them to us here on Earth. We cannot travel to them for close-up study. Even the Sun, the nearest star to us, is far enough away that we can only study the light that comes from it. Tell students that they will begin today's activity by looking at some images of the Sun.

3. Many Faces of the Sun Image Title Observations #3Radio sun Image
Additional Comments
#1 Sun in Visible Light
#2Infrared Sun Image
#3Radio sun Image
#4 Ultraviolet Sun Image
#5X-ray Sun Image
Explain to students that each image of the Sun was taken on the same day (September 18, 2000).
Have students write a brief description of each image in their notebooks. Students can include a description of the surface (smooth, grainy, dark, light, etc.), whether there are spots on the light or dark "spots" on the surface, or whether there are features extending out beyond the surface Have students recreate it in their notebooks.
Ask students to describe how each image differs from the other
Next slide

4. Infrared Image of the Sun Radio Wave Image of the Sun
Visible Light Image of the Sun
Infrared Image of the Sun
Radio Wave Image of the Sun
X-ray Image of the Sun
Ultraviolet Light Image of the Sun

5. Why do you think these pictures are so different?
The dark spots on two of the images and the bright spots on the other images are called sunspots.
Why do you think these pictures are so different?
That is what we will be investigating in this activity.
In the visible light image of the Sun, these spots look dark because they are cooler (6,000 °F) than the surrounding regions of the Sun (10,000° F).
Emphasize the differences in the sunspots and in the surface of the Sun in all of the photos.

6. What did that experiment show?
Think back to Sir W. Herschel experiment with the thermometers in the rainbow colors.
What did that experiment show?
Can you think of other types of radiation?
What causes sunburns?
How do you cook food quickly?
How do you look for broken bones?
What kind of radiation is in nuclear reactors?
It showed infrared is a form of radiation that we can’t see with our eyes.
Sunburn-ultraviolet
Cook quickly-microwave
Broken bones-x-rays
Nuclear-gamma rays

7. VISIBLE LIGHT How do wavelengths change along the spectrum?
Different colors have different wavelengths, with red light having longer wavelengths than blue or violet light.
Infrared radiation is just beyond the red, at longer wavelengths than visible light.
Ultraviolet radiation is just beyond the violet, at shorter wavelengths than visible light.
Before you look at Visible Light, Ask students to think back and tell you how do wavelengths change along spectrum.
Each click will bring in the next answer.
Have students write down in journal.

8. of the Electromagnetic Spectrum
Visible Light Region
of the Electromagnetic Spectrum

9. Electromagnetic Spectrum
Scientists have divided the electromagnetic spectrum into these different kinds of light, based on their wavelengths.
Gamma rays have the shortest wavelengths - less than 0.01 nanometers 1 x meters
Radio waves have the longest wavelengths, defined as anything over about 10 centimeters
Show and discuss EM spectrum picture and then have students write down the information one at a time.

10. Electromagnetic Spectrum

11. SUN FACES
These pictures of the Sun look different because they each show different wavelengths of energy that the Sun emits.
The only way we can learn anything about the Sun and other astronomical objects is to study the light that comes from them.
Studying light from different regions of the electromagnetic spectrum helps astronomers learn more about the Sun and other cosmic objects.
Explain the above one at a time.

12. Infrared Image of the Sun Radio Wave Image of the Sun
Visible Light Image of the Sun
Infrared Image of the Sun
Radio Wave Image of the Sun
X-ray Image of the Sun
Ultraviolet Light Image of the Sun

13. Scientists use different telescopes to take pictures of the Sun at different wavelengths; they can't use just one telescope to detect all wavelengths.
Telescopes
Have student copy info and then show slideshow.
You will need to use telescopes and satellites info sheet to give students some info on the sun images and the telescopes that took them.
Have students add notes about the telescopes used and what the image shows to their notes about the images of the Sun under the heading
“Additional Comments.”

14. Big Bear Solar Observatory (Southern California)
Visible Light Image of the Sun

15. McMath-Pierce telescope (Kitt Peak, Tucson, AZ)
Infrared Light Image of the Sun

16. Nobeyama Radio Observatory (Japan)
Radio Wave Image of the Sun

17. SOHO (Solar and Heliospheric Observatory) orbits the Sun
Ultraviolet Light Image of the Sun

18. Yohkoh satellite (orbits the Earth)
X-ray Image of the Sun
Yohkoh satellite (orbits the Earth)

19. TRACE satellite Transition Region And Coronal Explorer (orbits the Sun)

20. By the Light of a Star Student Activity Sheet
Read the questions below before you begin reading “By the Light of a Star.” Use your answers to the questions to fill in the table . An example has been started for you.
1.What are the different kinds of electromagnetic waves, in order from shortest wavelength to longest wavelength?
Use your answers to fill in the column “Different kinds of electromagnetic waves.”
2. What is an example of each kind of electromagnetic wave that people use, or are affected by, in everyday life?
Use your answers to fill in the column “Everyday example of this wave.”
3. What is an astronomical example (example from astronomy) of each kind of electromagnetic wave?
Use your answers to fill in the column “Astronomical example of this wave.”
You can make copies of this activity sheet or have students copy the above questions and chart on the next slide.

21. Shortest Longest Wavelength Different kinds of electromagnetic waves
Everyday example of this wave
Astronomical example of this wave
Shortest
Longest
Ultraviolet
Causes Sunburns

22. Remember !!!!!
That the only way that we can learn about the sun and other cosmic objects is to study the light that comes from them.
Astronomers need telescopes to collect and study that light.
You can give the students copy of By the Light of a Star Student Activity Sheet or let them copy the previous questions and this chart.

23. Problems that interfere with telescopes on the ground
The Problem
How do astronomers reduce this problem ?
Light pollution : surrounding light from cities makes it harder to see objects
Build telescopes far away from city lights
Size of telescope ; the bigger the telescope , the more light it can gather
Build bigger telescopes
Heat and wind; both can make it harder to see details in distant objects with a telescope
Build telescopes in arid areas with stable air.
Clouds and fog; both can make it harder to see details in objects through a telescope
Scattering of light by Earth’s atmosphere; particles in atmosphere scatter blue light more than red
Build telescopes on top of mountains above much of atmosphere or put telescopes in space.
You may need to modify in order to add demostration to chart.

24. Earth’s atmosphere prevents light at many wavelengths from reaching the ground.

25. Compare the image of the Sun on the right with that on the left, looking for changes.
Rotating Sun

26. Sun at X-ray Wavelengths
The TRACE satellite has provided spectacular images and movies of the Sun taken at X-ray wavelengths.

27. QUIZ! There will be a quiz next class. You should know
The types of waves ,in order of wavelength
How different types of waves are similar and different
Different factors that affect observations made with telescopes