The Universe Acording to Spectroscopy

Background

Spectroscopy is the study of the universe by looking at the spectrum that is emitted by an object. It is important that the students understand that the images that they see are created by computer models that using an algorithm (mathematical formula) convert the data that comes down from the satellite, which is numerical, into the images that we see. Also depending on the wavelength that is used to create the image, scientists can observe different features. This type of analysis is vital to the understanding of the composition of the earth and objects in the universe. This is a way that we can describe the atmosphere of other planets even though no one has ever been there. On Earth, the data from satellites is compared to data collected on Earth to validate the satellite data. This is called ground truthing. This method helps the researchers to create better algorithms for the models. This lesson is very extensive. If your schedule does not allow for each group to complete all of the activities in the EXTEND section, you could have different groups complete different steps and report to the class about the use of spectroscopy in the study of their area. A suggestion as to how to divide the Extend section is the following: Have all students complete steps 1-5 as they provide the basic knowledge for the rest of the activity and then assign one group step 6 (nebular studies), one group step 7 (individual stars- for this you will need to print the star chart and the spectral charts for the known stars for the group), one group step 8 (Sun), and one group step 9 (Earth). *One area that was not put in is the study of planets. If needed a group could do this by going to the USGS site http://speclab.cr.usgs.gov/maps.html and scrolling down to "Planetary" and using the sites under that, discover the use of spectroscopy in the study of the other planets in our solar system.

Knowledge/Skills Needed:

Review the relative sizes of the sun, moon, and Earth to help with the understanding of eclipses. A great site to help students understand size, go to http://www.exploratorium.edu/ronh/solar_system/index.html , and to determine the size of the moon, go to http://www.exploratorium.edu/ronh/solar_system/index.html . Students will also need to know the term’s aphelion and perihelion to understand the difference between a total and annular eclipse. A web site to help with this knowledge is http://www.exploratorium.edu/ronh/solar_system/index.html .

Procedure :

ENGAGE ACTIVITY

Have the students bring in old CDs or the free CDs that come in the mail. The cheaper the CD, the better. Make the smaller spectroscope (three on one page). You do not need the small tube that the picture shows. If the slit is to wide, use electrical tape to reduce its size.

You may want to start the lesson with several images of the earth and the universe taken by satellites and ask the question, "How do we get these pictures?" Make sure the students understand that the satellites do not take pictures like we do with a camera and film.

EXPLORE SECTION

If you have at your use a spectroscope and spectral tubes of different chemicals, set them up also and have students observe and draw those spectral lines. To get the charts that the students need to draw their spectra on, go to http://solar-center.Stanford.EDU/webcast/wcpdf/sun&stars5-8.pdf and scroll down to page 41 and print out page 41 and page 42 if you have gas tubes that students can observe.

EXTEND SECTION

Make sure to print out the star chart and the charts of the known stars’ spectrum for step 7. The charts are found at http://cse.ssl.berkeley.edu/lessons/indiv/timothyk/skymap.html .

ENGAGE Make a spectroscope. Go to http://www.uwm.edu/~awschwab/specweb.htm#moreinfo and follow the instructions for making a spectroscope. Make sure to darken the inside with either a black marker or black construction paper. Once you have the spectroscope made, look at different light sources in the room.

EXPLORE On the charts given, draw the spectra that you observe when looking at light sources. DO NOT LOOK DIRECTLY TOWARD THE SUN. Use color pencils to draw the spectrum. Try to draw the lines as close to the exact location you see in the spectroscope.

EXPLAIN In your journal, describe the similarities and differences you observe in the spectrums you drew. Based on this activity, describe ways that scientists can use spectral analysis to explore the universe. Read the following passages from "Image the Universe" website on spectrums and in your journal write a summary of the articles. Be sure to include in your summary the following:
What is a spectrum?

What are the different types of spectrums that can be used by researchers? How are each created?

What can a spectrum tell a researcher about an object they are looking at?

The sites to read are http://imagine.gsfc.nasa.gov/docs/science/how_l1/spectra.html and

http://imagine.gsfc.nasa.gov/docs/science/how_l2/spectra.html .

Go to http://amazing-space.stsci.edu/ and click on "Star Light, Star Bright" and complete the tutorial on light and spectra. Work through the tutorial and record in your journal, the main points you learned from each section of the tutorial. Explain how what you learned can be used by scientists as they study space using the spectroscope.

Go to: http://hawaii.ivv.nasa.gov/space/hawaii/vfts/oahu/rem_sens_ex/rsex.spectral.1.html

Go through the tutorial on how the images that you will see throughout this lesson can be made.

EXTEND The study of the universe is done by remote sensing. Many different satellites and telescopes have spectroscopes on them to analyze the universe.
1.Openhttp://junior.apk.net/~matto/spectroscopy.htm, click number seven "Types of Spectra".Read and answer the following questions in your journal:

What is the difference between an "emission spectrum" and a "dark line spectrum"? Which one is the type of spectrum produced by stellar material?

Return to the "Chemistry of Star" homepage.

2 Click on number eight and read the article on "Star Spectrum". Answer the following in your journal.

What are Balmer Lines? How can they be used to learn about stars?

3. Click on "spectral classification system" in reading under graph (c). Record down the seven spectral classes from the hottest to the coolest.

4. Click on "spectral sequence" in the last paragraph on the page. Answer the following in your journal-

As you look at the spectral sequence chart, are you looking at an absorption or emission spectrum? How do you know? Describe the general pattern you notice as you go from the hottest stars to the coolest stars.

5. Click "back" three times to return to the "Chemistry of Stars" homepage. Click on number nine, "Spectra of the different elements". Scroll down and view the spectrum of the different elements. Describe any problems you think you could encounter as you look at the spectrum of stars made up of several elements. Record them in your journal.

6. Open http://www.achilles.net/~jtalbot/data/nebula/index.html .

Scroll down to the chart and read the description of each category under the chart. Open the "data file" for the first nebula. You will see a series of number listed. This is how computers here would receive the data on Earth from the spectroscopes on a satellite. Using another set of the blank spectra charts (such as the ones in the Explore), use your color pencils to draw the lines on the spectrum to correspond to the wavelength. The first column is the wavelength and the second column is the intensity. If the intensity level is low, make the line thin, and if the intensity level is high, draw the line thick. Once you have completed this, click back and then click on "name" for the first nebula. This will give you the spectrum created by the same set of data as the spectrum you created. You will notice that the spectrum on the computer goes from violet to red, so you may want to turn your spectrum upside down to compare. Compare and describe your spectrum to the computer. Are there differences? Record your observations. Scroll down and observe the images of the nebula at different wavelengths. Models that turn the numbers into pictures create the images. Describe in your journal how scientists can use the images created from the data to learn about the nebula or any other body in space. Explain why the images need to identify what wavelengths they are showing.

7. Many of the spectroscopes that are used to study the universe are broad band spectroscopes to collect data in many different wavelengths in the electromagnetic spectrum. When studying new stars, scientists can compare their spectra to known spectra to determine the class of star they are looking at. Go to http://cse.ssl.berkeley.edu/lessons/indiv/timothyk/skymap.html and practice your skills in determining the class of stars that have been discovered by the EUVE satellite. On the star chart given to you, identify each star you click on and the class of star you determine it to be.

8. Spectroscopes are not used only to study stars outside of our solar system but they are used to study the most important star to us, the sun. Whereas many of the spectroscopes used to study the universe are broad based, the spectroscopes that study the sun are designed to collect data in very narrow wavelengths. Go to http://sohowww.nascom.nasa.gov/explore/EUVsun.html , and view the images of the sun taken by EIT instrument on the SOHO satellite. The color of the image is to help researchers to know what wavelength they are looking at. When the data is received from the satellite it is a series of numbers that are then turn into an image by a computer model. In your journal record down the wavelength, the temperature, the element, and the solar activity that can be seen in that wavelength. Describe the importance of looking at the sun in different wavelengths in terms of understanding solar activity. (Hint: Can you see sunspots in extreme ultraviolet?) In the "Go to" box at the bottom of the images scroll to "Education Links" Click on "Go to". From this page you can link to several different sites dealing with the sun. Scroll down to the "Daily Images" site and click on it. Look at the images of the sun taken in x-ray and visible. Journal write- Do you see any relation between the x-ray images, the visible images and the ultraviolet images? Explain the importance of studying the sun in many different wavelengths.

9. Spectroscopy is not used only for the study of stars. This field is also used to study our Earth and other planets. Go to http://speclab.cr.usgs.gov/maps.html and scroll down to "Introduction to Imaging Spectroscopy Results" and click and read the information on spectroscopy. Journal Write- Make a chart that shows the progression of remote sensing from black and white photographs through electronic absorption. Describe the advantages and disadvantages of each form of remote sensing mentioned in the reading. Click "Back" and scroll down to the section called "Environmental Applications". Click on "Summitville Mine". Read the first four paragraphs to understand how image spectroscopy is used by the USGS and how the images are obtained. The data from the satellite is feed into the computer model that creates the images based on an algorithm (mathematical formula). Scroll down to the first image and read the paragraph above the image. Click on the image to enlarge and scroll down to the key and look at the types of minerals located in the Image. Record down the major mineral(s) found around the Summitville mine. Click back and record the wavelength that this image is based on.

Scroll down to the second image and read the paragraph above the image. Click on the image to enlarge. Scroll down to the key and look at the types of minerals located in the image. Record down the major mineral(s) found around the Summitville mine. Click back and record the wavelength that this image is based on . Read the "Discussion and Summary".

Read the "Discussion Journal Write: Explain why images need to be made in different wavelengths. Describe the application of imaging spectroscopy to studying environmental science.

EVALUATE Students working alone or in groups, research different applications of image spectroscopy. They can prepare posters or power point presentations for the use of spectroscopy in the study of the earth, the sun, the planets, or the universe. Some of the information that should be included in their presentation: the satellite(s) where the data came from, the wavelength(s) used to collect the data, the information we have learned using spectroscopy, and future missions if applicable. Some sites to start looking for the information : Earth and planets: http://www.jpl.nasa.gov/pictures/earth/aviris.html ,
http://speclab.cr.usgs.gov/index.html , http://TES.asu.edu/ , http://landsat.gsfc.nasa.gov/ , http://seawifs.gsfc.nasa.gov/SEAWIFS.html ,

http://las.saa.noaa.gov/, http://toms.gsfc.nasa.gov/

List of resources for all topics:

http://www.techexpo.com/WWW/opto-knowledge/IS_resources.html ,

http://www.earth.nasa.gov/

Sun:

http://sohowww.nascom.nasa.gov/,

Hubble Space Telescope (planets and universe):

http://www.stsci.edu/

Chandra (universe):

http://chandra.harvard.edu/about/axaf_mission.html

Imagine the Universe cite ( universe)

http://imagine.gsfc.nasa.gov/docs/sats_n_data/sats_n_data.html