Astronomy Lab

Procedure

1. Roll the construction paper into a tube 4 inches in diameter; secure with masking tape.

2. Mount the grating on one end of the tube using tape.

3. Set the 3 x 5 in. index card face down on a table, place the open end of the tube on it and

with a pencil draw a circle around the tube on the card.

4. Place the index card on a sheet of cardboard to protect the table. In the middle of the circle

you drew, cut a slit 2.5 cm long and 0.5 mm wide, using scissors and a ruler to make the

edges very clean. (You may need a few tries to get this correct.)

5. Cut out the circle with the slit.

6. Align the long axis of the slit so that it is perpendicular to the width of the grating slide.

Tape the slit to the open end of the tube (opposite the grating) with the masking tape. Be

sure to cover as much of the end of the tube as possible, leaving the slit open. Color the

tape with the permanent marker.

7. To use the spectroscope, point the slit at a light source and look through the diffraction

grating with your eye a few inches from the grating. Move the tube so that you can see the

light source clearly. Look slightly left or right of the slit to visualize the spectrum of the light

source. You may need to slightly rotate the spectroscope to clearly visualize the spectrum.

NEVER STARE AT THE SUN AS THIS CAN CAUSE SERIOUS AND PERMANENT EYE

DAMAGE!

8. Using the spectroscope, visualize the spectra of an incandescent light bulb (typical bulb

found in a household lamp), a fluorescent light (typically found in classrooms, hallways,

store interiors, etc.), and a street lamp.

Questions

1. Describe how the spectra from each light source differs from the others. What accounts for

these differences?

2. How would the spectra of other light sources (for example: TVs, metal halide bulbs, fire)

compare to those from #2 above? How would you use these spectra to determine what

comprises these light sources?

Procedure

1. Cut a 2.5 x 2.5 cm. hole in the center of the cardboard. Note: you can use your kit box lid

for this material.

2. Position a square of aluminum foil over this hole and tape to secure it in place.

3. Using the push pin, create a small hole in the center of the aluminum foil.

4. Tape the pin hole viewer to 1 ruler at the 2 inch mark. Tape the index card to the ruler at

the 8 inch mark.

5. To measure the diameter of the sun, hold the pinhole viewer so that the light from the sun

passes through the hole on to the sheet of white paper.

6. Measure the diameter of the image from the sun on the index card.

7. Measure the distance from the pinhole to the piece of paper.

8. Record your measurements in the table below.

9. Move the index card to the 11 inch mark on the ruler and repeat Steps 6-8.

10. Use the following equation to determine the diameter of the sun:

Diameter of sun = (diameter of image / distance from pinhole to paper) * distance earth to sun

Post-Lab Questions

1. What is the diameter of the sun using your pinhole viewer? How does your determined diameter

compare to the accepted diameter of the sun?

2. Use the viewer to determine the moon’s diameter (use it on a night with a full or near-full

moon). How does your determined diameter compare to the accepted diameter of the

moon?

3. How much larger is the sun than the moon? Why do both appear the same size in the sky?