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Exploring Light
Brief Summary
This exhibit allows visitors to experiment with light and
colors. They can break light up into its spectrum of
colors, block certain parts of the spectrum to see what
color remains, mix parts of the spectrum to form new
colors, and do other color- mixing activities. They can
also use a spectroscope to analyze the colors to see what
spectral colors they are made from.
Main Teaching Points
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Light can be broken down into its constituent colors.
Combining all of the parts of the visible light spectrum yields white light. However, if you
combine light from only a portion of the spectrum, you will get a different color.
You can use a spectroscope to analyze the color composition of a sample of light and
determine the history of that light.
Astronomers use spectroscopes to analyze the light coming from stars to determine how
the light was produced.
Educational Strategy
This exhibit allows visitors to experiment with color mixing in a very hands-on way. It also
allows them to follow the history of the light starting at its source (the bulb) as it is broken up,
filtered, recombined, and perceived in their eyes. This exhibit is very aesthetically pleasing,
so that many visitors will enjoy it for that reason alone, even if they are not interested in the
scientific principles that it demonstrates. It is grouped with Seeing the Sun and Infrared
Experiments so that this area of Space Odyssey covers different aspects, in different ways, of
a fundamental concept in astronomy: Studying objects by monitoring and analyzing light.
Suggested ways of facilitating this interactive
Try this:
 Show how you can create different colors using different sliders.
 Show how the sliders block different parts of the spectrum and the color in the
circle is the result of recombining the part of the spectrum that was not blocked.
Or, try this:
 Use the spectroscope to look at the colored circle.
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How does what you see in the spectroscope relate to the parts of the spectrum that
you blocked with the sliders?
Questions and Answers
What does this have to do with space science?
Astronomers use spectroscopy to study the light from stars and determine how that light was
created. Each of the parts of that process has an analog in this exhibit. The light bulb
represents the star where the light is produced. The slider represents the atmosphere of the
star where some of the light is blocked by various components. The circle of colored light
represents the light from the star as it is seen from the Earth. The spectroscope is used to
analyze the light and determine its history, just as astronomers use spectroscopes to analyze
starlight to determine the composition of the star, the atmosphere of the star, and other
intervening objects (such as clouds or the Earth’s own atmosphere) which might have
impacted the light on its journey to Earth.
Why do colors mix to form a single color?
The reason you see a single color is because of the way your eyes and brain work, and has
nothing to do with the physics of light. For example, if you mix green light with red light it will
appear yellow to your eye. It will look just like the yellow part of a spectrum (spectral yellow).
However, if you look at the yellow light made from red and green in a spectroscope you will
not see any yellow bands. You will only see green and red bands. If you look at spectral
yellow light through a spectroscope you will see a yellow band. Light that may look the same
to the human eye and brain may look very different in the spectroscope, which shows what
the light is really made of.
Demo: You can see this effect using the Gas Tube Spectroscopy activity.
Other Cool Stuff to Try
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Use the prism sliders to break the spectrum into two parts. The colors of each of these
parts are complementary to each other. That is, they recombine to form white light.
Use colored filters from the Gas Tube Spectroscopy activity in conjunction with this
experiment.
Operating Tips
Potential Problems
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Background materials
collections links)
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(websites,
videos,
articles,
digital
http://csep10.phys.utk.edu/astr162/lect/light/absorption.html – absorption and emission
spectra
http://mo-www.harvard.edu/Java/MiniSpectroscopy.html – spectroscopy interactive
http://antwrp.gsfc.nasa.gov/apod/ap000815.html – the solar spectrum