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Build Your Spectroscope

Scientists use spectroscopes to analyze the elemental composition of a star. Learn about spectroscopes and how they work, then, build your own spectroscope to analyze the composition of Earth's atmosphere, the moon, and even light bulbs.

Video Courtesy of NASA

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  • Cereal Box (regular size or larger, emptied)

  • Old/used, discarded CD or DVD

  • Tape

  • Scissor

  • Ruler

  • Construction paper (optional)

  • Aluminum foil

  • Printable cutout sheet for this activity (found at the bottom of Cosmoto's "Week 2" site page)

Step 1

Use your scissor to make a thin slit (0.5 cm thick) at the top of one end of the cereal box.


(Optional: To give your spectrograph a uniform appearance, cover the surface areas of the cereal box with construction paper.)

Step 2

Turn the cereal box so that one of the large sides of the box is facing you and is positioned horizontally. Use a ruler to draw a straight line from one end of this side, that lines up with the slit, to the other end of this side of the box. Draw this same line on the opposite, large side of the cereal box. 

Step 3

From the printable cutout sheet for this activity, use the angle cutout to draw a 60 degree angle.  This angle should be drawn just  below the line you drew, and on the end that is farthest from the slit.  Draw this same angle on the other side of the box, just below the other line you drew.

Step 4

On the thin side of the cereal box, draw a line connecting the two lines that you already drew. Cut through both the angle lines and through the line on the thin side. 

Step 5

On the thin side of the box that is just above the angle lines you cut, use your scissor to make a small hole directly above the angle lines you cut.

Step 6

Insert a CD or DVD into the angle lines that you had cut into the cereal box. When inserting the CD (or DVD), make sure that the hole in the middle of the CD (or DVD) is not inside the cereal box.

Step 7

Tape the CD (or DVD) in place to the cereal box. Wrap all parts of the CD (or DVD) with aluminum foil to prevent any unwanted light from entering the cereal box.


You have now completed your spectroscope!

Point the slit of the spectroscope at a light source (the sky or a bulb) and look through the hole directly above the CD (or DVD) to view the spectrum of the object you are observing. Do NOT point your spectroscope directly at the sun. The spectrum you see should look similar to the image below:


Image has been enlarged

Step 8

Record the spectrum of each object you observe on the printout sheet. Look for a difference in the observed spectrum between the sky, light bulbs, and the moon. If a color is missing from the spectrum, that is a difference. If you see a difference, you have successfully detected differences in the chemical compositions of your light sources!

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