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 2004 Yerkes Summer Institute
August 7 - 13, 2004
Yerkes Observatory in Williams Bay, WI
Theme: What Are Stars Made Of?
Participants: 23 students; 19 instructors; 40 parents, siblings, and younger students.
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The Yerkes Summer Institute (YSI) is memorable experience that serves as a capstone to a year of science
enrichment activities for inner city middle and high school students in the Space Explorers Program. It is a
one-week, immersive, residential, science program held at the beautiful and historic Yerkes Observatory, which is
located in Williams Bay, WI above the shores of Geneva Lake. The institute's long duration and all-day schedule
allows the students to delve deeply into the process of scientific inquiry. This structure also facilitates extended
discussions and interactions between researchers and students, as well as peer-to-peer communication. The
instructional staff is a mix of research scientists and educators, a mixture, which allows the students to reach new
levels and ensures that the activities remain meaningful to the students.
This summer the Space Explorers investigated spectroscopy with the theme: What are stars made of? Through
a series of related laboratory explorations the students delved into the fundamentals of spectroscopy and its
application to astronomical objects. They studied an assortment of spectra from pure elements and pure food
coloring dyes to complex mixtures in solar, stellar and galactic spectra. In some cases the challenge was to
produce the spectra and in others to analyze it.
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Institute Schedule & Background (PDF format)
What is Spectroscopy? (PDF format)
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Instructors: Robert Friedman, Matthew Kyle Sharp & Carlos Cunha
This lab demystified the spectrometer by creating a human sized optical array and spectra with dimensions of feet.
The students first investigated individual optical components: lenses, mirrors, and diffraction gratings. Once they
understood the basic behavior of light with these optical elements including variation with wavelength, they
assembled them to construct a massive spectrometer. The system was calibrated using red and green lasers with known
wavelengths. Next, spectra of known elements from discharge tubes were projected through the calibrated system.
The students combined these elemental spectra with a giant projection of the solar spectrum to deduce the basic
elemental composition of the sun.
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You Are the Spectrometer, by Robert B. Friedman & Matthew K. Sharp (PDF format)
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Instructors: Sarah Hansen, Monica Valluri & Doug Rudd
In this laboratory, students constructed their own hand-held spectroscopes and used them to determine the identity
of "unknown" elements in discharge tubes. Armed with these individual elemental spectra, they then examined the
spectra of a range of stars, and determined which elements had left spectral fingerprints on each star. From the
presence of different elements and some basic data on the nature of stars, they were further able to estimate the
temperatures of these stars. In the "mixed-up group" extension activity, the students used a web based computer
model to examine how the spectra of galaxies can be synthesized by assembling a weighted combination of different
types of stellar spectra (see Doug Rudd's activity).
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Fingerprinting the Stars, by Sarah Hansen & Monica Valluri (PDF format)
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Instructors: Randy Landsberg & Bill Fisher
This lab served as tangible real world connection to the more distant astronomical spectra as the students examined
FD&C food colorings in consumer products such as Gatorade. The first step was to use the spectrometer as a
wavelength specific light source in order to probe the relationship between wavelength and color. Next, with
visible spectrum in hand, the students examined the spectra of pure dye colors: red, blue, yellow, etc. between
400-800nm. Finally they explored more complicated mixtures (purples, greens, etc.) and utilized their earlier data
to determine the components of these mixes. An analogy was made between the use of spectroscopy to identify
component dyes of a colorful solution with how astronomers analyze stars to determine their elemental composition.
Note: the colors used came from pure FD&C (Food, Drug and Cosmetic) food colorings that are considered safe for
consumer products such as M&Ms or Gatorade.
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What's in the Mix? Liquid Color Spectroscopy, by Randy Landsberg & Bill Fisher (PDF format)
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Instructors: Sarah Hansen & Erin Sheldon
This lab provided a visceral connection to astronomical spectra by allowing the students to view spectra directly
with a telescope that had a diffraction grating inserted before the eyepiece. It helped to extend the basic message
of the day labs, "that the light emitted and transmitted by objects and materials (e.g. spectra) can reveal a lot
about the makeup of an object", to the composition of distant objects such as stars and galaxies. This lab offered
the students the opportunity to observe directly how light from stars can be split into a visible spectra with
features that have an understandable physical origin (e.g. the spectra were in the shape of the observed object).
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Instructors: Chris Greer, Vivian Hoette & Andy Puckett
This quantitative lab employed a telescope-mounted prism and CCD camera to take digital images of spectra of
astronomical objects. These black and white spectral images were then analyzed with a computer to determine the
brightness at each wavelength (color) of light. Analysis of these discrete line spectra revealed stellar
composition and temperature, and the elemental composition of nebula.
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Instructor: Eileen Sheu
This investigation brought the students back to the early terrestrial roots of spectroscopy - almost all the way
back to the days of alchemy. They used flame tests to perform elemental analyses with the spectroscopes they had
constructed in the day lab. A series of stations were assembled where assortments of metal chloride salts (e.g.,
NaCl, BaCl, CuCl2…) could be consumed in flames from propane torches to reveal fundamental colors and emission line
spectra associated with each element. The students compared the observed colors and spectra to a series of know
spectra to determine which element was responsible for each colorful flame.
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