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• Introductory Lesson: 60 minutes
• Learning Activity: 60-90 minutes
• Culminating Activity: 30-45 minutes
How is it that astronomers know many of the gases that make up
the Sun if they have never visited it? How do they know what minerals
make up the surface of Mars? How do they know that Betelgeuse
is a dying star if it is so far away? How have they been able
to detect the existence of white dwarfs and black holes? What
clues do they use to unravel the mysteries locked in the stars?
Astronomers have discovered how to use information that the stars
and other objects give off in the form of light to learn more
about them. Light carries lots of information. It tells us about
the existence of objects we can’t even see and about their
composition. From the light emitted by an object we can find out
its composition, temperature, density, motion, and magnetic field.
The sun and the stars send us both visible and invisible light.
An important concept to understand is that light travels in waves.
Invisible light has wavelengths that are either longer than visible
light, such as infrared, microwave, and radio waves; and wavelengths
that are shorter than visible light, such as ultraviolet, x-ray,
and gamma waves. When the light from the Sun or stars is displayed
according to its wavelength, it is called a spectrum. A
wave has several characteristics. The highest part of a wave is
called the crest. The lowest part of a wave is called a
trough. The wavelength is the distance from one crest
of a wave to the to the next or from one trough of a wave to the
next, and it an be measured with a basic unit of meters (m) such
as centimeters, or Angstroms. One Angstrom unit is one
ten-millionth of a centimeter. It is easy to see from this that
an Angstrom is an extremely small unit of measurement. Frequency
is the number of complete waves, or wavelengths, that pass a given
point each second. All light travels at the same speed, but each
color has a different wavelength and frequency. As the wave frequency
increases, the wavelength decreases. The amount of energy carried
depends on the wavelength. The shorter the wavelength, the more
energy it contains; the longer the wavelength, the less energy
is contains.
Like everything on Earth, objects out in space are made of atoms.
An atom is the smallest unit which can be identified as any particular
element. There are about 100 different kinds of known elements;
therefore, there are about 100 different kinds of known atoms.
Each different type of atom emits light waves at a combination
of wavelengths that are special to that particular type of atom.
These light waves are emitted as emission lines. Every
chemical element has a signature print of its own that can be
used to identify it. When looking at spectra from objects like
stars and planetary bodies, it is possible to identify the chemical
elements present by matching the colored spectral lines with the
elements’ spectral signature.
Spectroscopy is a scientific technique that is used by
scientists to determine the composition of objects. Spectroscopes
are instruments used to analyze the amounts and types of spectral
light that comes from different objects. A spectroscope breaks
down the light emitted or absorbed by chemical elements into specific
lines of color. There are three basic types of spectra that can
be observed with a spectroscope. They include: continuous spectra
which show all of the colors of the spectrum blended next
to each other in a band, absorption spectra which can be
identified by the black bands of missing color present in a continuous
spectra and emission spectra, which can be identified by
the bright bands of color present on top of a continuous spectra.
In addition to the invisible spectra that are made visible by
the use of spectroscopes, humans can observe with the naked eye
the spectra that make up the visible spectrum. Astronomers
are using spectral analysis in their study of the surface of Mars.
They have created an instrument that identifies and analyzes the
spectra being emitted from Mars’ surface to determine what
the composition of the surface is.
In this lesson, students will
learn how to identify the different kinds of spectra, how to use
a spectroscope, and how to identify certain elements based on
their spectral signature. They will be introduced to the THEMIS
instrument on board the Mars Odyssey spacecraft and understand
its importance in the Mars Odyssey 2001 Mission. As a culminating
activity, students will apply the knowledge gained to determine
the identity of two mystery elements recorded in the rocks on
Mars by Mars Sojourner in 1997.
Science
Students will be able to:
• Explain the difference between emitted and absorbed light
• Draw and label each type of spectrum: visible, absorption,
and emission
• Identify an element by its spectral signature
• Use a spectroscope to identify certain types of light being
emitted from light sources
• Explain the purpose of the THEMIS instrument aboard the
Mars Odyssey spacecraft
National Science Education Standards
http://bob.nap.edu/html/nses/html
Content Standard A: Abilities necessary to do scientific
inquiry
Understandings about scientific inquiry
Content Standard B: Properties and changes of properties
in mater
Transfer of energy
Content Standard C: Earth in the solar system
Content Standard E: Understandings about science and technology
Content Standard G: Science as a human endeavor
State Standards
Louisiana Framework for Science
http://ww.lcet.doe.state.la.us/doe/assessment/standards/SCIENCE.pdf
SI-M-A1: Identifying questions that can be used to design
a scientific investigation.
SI-M-A2: Using mathematics and appropriate tools and techniques
to gather, analyze, and interpret data
SI-M-A4: Developing descriptions, explanations, and graphs
using data
SI-M-B2: Communicating that current scientific knowledge
guides scientific investigation
SI-M-B6: Communicating that scientific investigations can
result in new ideas, new methods or procedures, and new technologies
PS-M-A1: Investigating, measuring, and communicating that
properties of different substances are independent of the amount
of the substance.
PS-M-A2: Understanding that all matter is made up of particles
called atoms and that atoms of different elements are different
PS-M-A4: Understanding that atoms and molecules are perpetually
in motion
PS-M-C3: Understanding that the sun is a major source of
energy and that energy arrives at Earth’s surface as light
with a range of wavelengths
PS-M-C4: Observing and describing the interactions of light
and matter
ESS-M-A5: Identifying the characteristics and uses of minerals
and rocks and recognizing that rocks are mixtures of minerals
ESS-M-C1: Comparing and contrasting the celestial bodies
in our solar system
ESS-M-C8: Understanding that space exploration is an active
area of scientific and technological research and development
Videos:
Passport to Knowledge—Live from Mars
Web sites:
Spectra of Gas Discharges
http://home.achilles.net/~jtalbot/data/elements/index.html
Students can access examples of spectral data of certain gases
as they would appear in a spectroscope. This applet produces JPEG
images of what elemental gas discharges look like in a visual
spectroscope. Teachers can use these examples if they do not have
access to gas discharge tubes or spectroscopes.
Spectra of Different Atoms
http://www-astronomy.mps.ohio-state.edu/~pogge/Ast162/Intro/Spectra/index.html
Another site that students can access to find samples of spectral
emission lines of specific atoms. Teachers can also print these
examples to use in teaching students how to identify different
elements by their spectral signatures.
For every two students:
• glass or plastic prism
• copy of the electromagnetic spectrum
• spectral line samples master sheet and cut-out strips
• colored pencils
• black sharpie markers
• examples (pictures) of the types of spectra: absorption,
emission, visible
• spectroscopes (website included that tells you how to make
your own)
• incandescent light bulb
• chemical light stick (each one lasts four hours)
• fluorescent light source
• plant grow light bulb
• several spectrum tubes (if available) (one should be mercury)
Prior to beginning the lesson, CUE the video Passport
to Knowledge—Live from Mars to beginning of tape.
Bookmark the Web sites used in
the lesson on each computer in your classroom or the computer
lab.
Preparation for the hands-on
elements of the lesson
1. Print copies of the handout Spectra of Different Atoms found
at the Web site
http://www.astronomy.ohio-state.edu/~pogge/Ast162/Intro/Spectra/
(two handouts per two students) and laminate them.
2. Cut out one set of the spectra lines for each group of students,
making sure to remove the names of the elements
3. Place the cut-out spectral strips into an envelope, being sure
to rearrange the order before placing them in the envelope.
4. Assemble spectroscopes and light sources for students.
5. Make copies of all worksheets and handouts for students.
1. Brainstorm with students what they know about the planets,
the Sun, and other well-known stars. Make a list on the board.
After enough discussion, ask students how scientists gather information
about objects in space. Circle all answers that indicate technology
being used to obtain the information. Ask students what each circled
item has in common. (They should be able to identify that a type
of technology was used by scientists to learn most of the information
about other planets, the Sun, and the stars that we know. Optical
and radio telescopes are examples.)
2. Provide students with a FOCUS
FOR MEDIA INTERACTION, asking them to pay particular attention
to the types of technology that were needed to get scientists
to the stage of development known as Odyssey 2001. PLAY
the first segment of the video Passport to Knowledge—Live
from Mars. Be prepared to PAUSE the video after
hearing these words from Kurt Williams, the host, “Lots to
do, lots to see, let’s get going.” (After viewing the
video clip, ask students what technology was used. They should
be able to identify some of the following: space station, space
shuttles, surface mappers, retrorockets, orbiters, landers, rovers,
balloons, airplanes, subsurface explorers, life detection instruments,
telescopes, advanced communication, satellites, solid rocket boosters,
solar arrays, etc.)
3. FAST FORWARD the video
to the segment right after Kurt Williams says, “But first,
the missions that proceeded Odyssey...What did they find out and
what is left for Odyssey to discover?” CUE the video
to show the night sky against a landscape. Prior to viewing this
segment, ask students to identify and/or describe earlier Mars
missions they know of and whether or not they were successful.
List them on the board. PLAY the video segment. Provide
students with a FOCUS FOR MEDIA INTERACTION by asking them
to record the names of the previous Mars missions mentioned in
the video segment. After viewing the video segment, have students
identify the mission’s names and purposes as you write them
on the board. (Through this activity, help students to understand
that the knowledge we have about Mars and other objects in space
is gathered through careful, methodical scientific endeavors,
each one building on the knowledge gained from the previous one,
and the important role technology plays in every mission.)
STOP the video after you hear the words, “And that’s
where Mars Odyssey, 2001, comes in.”
Mars Missions:
• Mariner 4—flew by and sent back 21 images of Mars
• Mariner 9—orbited Mars and sent back images of volcanoes,
a huge canyon, and channels
• Mars 2—first spacecraft to land on Mars
• Two Viking Landers—performed experiments to determine
the existence of life on Mars and sent back images
• Mars/Pathfinder—used air bags to bounce down on planet,
safely landed on the surface of Mars
• Mars Sojourner—Rover that analyzed rocks close to
the landing site showed us rocks that could have been formed by
sedimentation and sand dunes that might have been created by long
exposure to water
• Mars Climate Orbiter—was lost due to a mix-up confusing
miles and meters
• Mars Polar Lander—carrying two probes designed to
look for water beneath the surface crashed during its descent.
• Mars Observer—contact was lost
• Mars Global Surveyor—has an laser altimeter that has
mapped the elevation of the Martian surface in great detail. A
device that senses the heat energy of the surface has shown us
places with minerals that usually form in long standing. Its camera
has returned pictures. It has sent back information about the
surface characteristics of Mars, its magnetic fields, and the
atmosphere of Mars.
4. REWIND the tape to the
segment that shows the interview with Vicky Hamilton discussing
THEMIS and how it works. Ask students to review the list created
at the beginning of the lesson about how scientists have learned
about the Sun and other planets. Provide students with a FOCUS
FOR MEDIA INTERACTION, asking them to identify what new technology
will be aboard Odyssey 2001 and what it’s purpose will be.
RESUME PLAY with the interview with Vicky Hamilton. PAUSE
PLAY after the interview with John Callas about the Gamma
Ray Spectrometer. Have students identify the two instruments that
are aboard Odyssey and explain their purposes.
In this activity, students will learn about the electromagnetic
spectrum and specifically, about how scientists use invisible
wavelengths that are part of it in their exploration of other
planets. They will identify the three basic types of spectra:
emission, visible, and absorption and learn how each is used to
identify certain elements. Students will become familiar with
the spectroscope and use it to identify specific elements.
1. Tell students that the purpose
of this lesson is gain an understanding of the electromagnetic
spectrum and how it is used by scientists to explore other planets
and stars. Since the instruments aboard Odyssey use the electromagnetic
spectrum in their analyses of rocks and other significant planetary
data, students will gain a rudimentary understanding of how it
is done by doing this activity. Students should understand that
all light travels in waves, some visible and some invisible. The
light that your eyes can see is known as visible light. Different
wavelengths of visible light are seen as different colors by your
eyes.
2. Perform the following
activity to help students understand the colors that can be seen
in the visible spectrum. Hold a glass or plastic prism in a beam
of sunlight. Hold your prism so that sunlight streaming through
a window can pass through it. Carefully turn the prism until you
obtain a bright “rainbow” of colors on the wall or ceiling.
If sunlight is not available, you can use a light bulb as a light
source. Have students use colored pencils to draw the visible
spectrum (Worksheet 1). Once students understand that the
light we can see is visible light and it can be broken up into
different wavelengths of color, tell students that the Sun and
stars also send us invisible light that has either longer wavelengths
or shorter wavelengths. When placed in order from increasing to
decreasing wavelength or from to increasing wavelength, scientists
have created an electromagnetic spectrum. Give each student
a copy of the electromagnetic spectrum (Student Sheet 1).
3. Show students a spectroscope.
Explain to students that a spectroscope is an instrument used
by scientists to break light being emitted from a particular object
into its various wavelengths, thereby enabling the viewer to “see”
the wavelengths (colors) of which it is made. Explain that every
chemical element has a “fingerprint” of its own which
can be used to identify it. By matching the colored spectral lines
seen in the spectroscope with the element’s spectral fingerprint,
it can be identified. Give each student samples of the spectra
exhibited by certain elements (Worksheet 2). These can
be downloaded from the Web site called “Spectra of Different
Atoms” mentioned above under Web sites. Separate each example
and remove labels that identify them. Have students identify the
elements by matching them with a master sheet identifying each
atom. Check for accuracy. Have students describe one atom’s
spectrum, identifying the colors of the lines shown and their
frequency. In their description, students should mention the degree
of brightness seen and where most of the lines occur.
4. Give each pair of students a
spectroscope and three light sources to use. Use an incandescent
light bulb, fluorescent bulb, and a sodium vapor light (if possible).
Have them identify the atoms being emitted from the light source.
Check for accuracy. If spectroscopes and/or discharge tubes
are not available, students can view images of elemental gas discharges
by accessing the Web site called “Spectra of Gas Discharges”
at http://home.achilles.net/~jtalbot/data/elements/index.html
Directions for creating your own spectroscopes can be found at
the following Web site: http://www.exploratorium.edu/snacks/spectra.html
5. Once students have had practice
identifying elements by their spectra, introduce students to examples
of the visible spectra, emission spectra, and absorption spectra.
Give students examples of each (Worksheet 3) and have them
match the explanation for each with the type of spectrum it should
display. (Students should say that the visible spectrum shows
all of the colors: red, orange, yellow, green, blue, indigo, and
violet. The absorption spectrum shows the visible spectrum
with black lines showing up where certain colors are absorbed.
The emission spectrum shows a black background with bright
lines of color showing up where certain colors are emitted.) Different
elements show different types of spectra. The spectral lines that
are displayed help scientists determine what elements make up
stars and planets without ever visiting them.
Present the following scenario to students: (Worksheet 4)
Sojourner, the rover carried by
Mars Pathfinder, rolled out onto the surface of Mars on July 4,
1997, to analyze rocks close to the landing sight. Some of the
information gathered by Sojourner was in the form of spectral
data. This data was used to determine the composition of some
of the Martian rocks. Use the data given by the teacher to determine
the mineral composition of the rocks analyzed by Sojourner.
1. Provide students with two spectral
strips to identify. Have students access the Web site “Spectra
of Gas Discharges” to use when trying to identify the two
spectral strips, or give students a master sheet of spectral strips
to use when identifying the mineral found in the sample.
2. Students will compare the lines of emission or absorption on
the spectral strips with the master sheet and determine the element
that is present.
3. Students will use colored pencils to copy the spectral strip
onto worksheet. Students will then describe what is seen and how
it proves that the mineral identified is correct.
Social Studies/Technology: Create a time line of the history
of Mars’ exploration using TimeLiner Software by Tom Snyder.
Science and Language Arts: Research one of the elements
studied to determine when it was discovered, what its atomic structure
is, and any uses for it. Prepare a written report, using Claris
Works or Microsoft Works.
Technology: Research the types of technology that have
been invented to further the space program using internet sources.
Select one type of technology and identify all of the Mars Missions
that have used it. Find out what was learned about Mars as a result
of its use. Present it to the class using a form of technology
such as Hyperstudio, Claris Works Slide Show, or
Power Point.
• Invite a scientist from Stennis Space Center to visit the
class to talk to the students about space exploration and the
recent events concerning Odyssey. Ask him/her to bring current
images from Odyssey that have been sent back to NASA.
• Have a geologist visit the class to discuss the minerals
found in different rock types and how scientists use mineral identification
to learn more about the history of the Earth.
Student materials include:
1. Worksheet 1—copy of “The Visible Spectrum”
HTML PDF
2. Student Sheet 1—illustration of “Electromagnetic
Spectrum” from the Enviro-Tacklebox™ Web site: http://www.envirotacklebox.org/modules/m1uv.htm
HTML PDF
3. Worksheet 2—”Spectra of Atoms” from Web
site: http://sciencejoywagon.com/physicszone/lesson/09waves/spectrum/emisndop.htm
4. Spectra striips in envelopes (Prep for Teacher #2/3)
5. Worksheet 3—Types of Spectra HTML PDF
6. Worksheet 4—Culminating Activity HTML PDF
