Compare and contrast natural versus anthropogenic climate changes. Include at least two (2) specific examples of each.

Diameter of the Sun Activity (25 points)

Brief Overview of Activity: A pinhole can form an image in much the same way as a lens. Measuring the size of the Sun’s projected image and the distance between the pinhole and the image, you will be able to calculate the diameter of the Sun.

Required Items: a friend to help you, a broom handle (or mop handle or long straight piece of wood of similar dimensions), a ruler (marked in centimeters), two envelopes (or two 5 x 7 index cards), a pencil, masking tape, one stickpin.

Number of Observations needed: 1

Timing of Observations: near noon on a bright sunny day


Preparation: Use the stickpin to poke a small hole near the center of one of the envelopes. Mark a location near the top of the broom handle with masking tape (this is where your friend will hold the envelope with the pin-hole). Mark another location near the end of the broom handle with masking tape (this is where you will observe and mark the image). Carefully measure the distance between your two marked locations on your broom handle. Make your measurement to the nearest 0.1 centimeter and record here: ___________ cm.

Observation: Caution: never stare directly at the Sun. Gather your friend, marked broom handle, two envelopes, pencil, and then head outside. With your friend holding the envelope with the pinhole at the upper marked position and you holding the other envelope at the lower marked location, align the broom handle such that a small faint image of the Sun’s disk is seen on the lower envelope. You may find it convenient to actually sit on the ground for this procedure. With a pencil, carefully mark the location of opposite sides of the Sun’s disk. Here is a link showing a diagram of the setup.

Calculation: From your marked envelope, carefully measure the size of the projected image of the Sun’s disk to the nearest 0.1 centimeter and record here: __________ cm.

Next, use the relationship below to calculate the Sun’s diameter in kilometers. Note that the distance to the Sun is 1.5 x 10 8 km.

    Sun's diameter in kilometers              image diameter in centimeters
------------------------------------- = ------------------------------------------
 Distance to the Sun in kilometers       distance between image and pinhole in cm

Record your calculated value for the diameter of the Sun ______________________ km

Setup Diagram

Moon Position Activity (25 points)

Brief Overview of Activity: Over a period of at least three consecutive evenings, you will make careful observation of the Moon’s changes in appearance and position.

Required Items: a notebook to take notes or make a sketch (bring your red flashlight), you may take digital photos if you wish.

Number of Observations needed: 3

Timing of Observations: 3 consecutive nights, around (and after) sunset, a few days after the Moon is new. Your instructor will inform you what the appropriate viewing days are in the term.


Choose a location with a good view of the western horizon from which you can clearly observe the Sun at sunset. Since we will be timing our observations a few days after the Moon is new, the Moon should be visible in the sky at (and for a while after) sunset. It is important that you make all of your observations from the same location and at the same time. You may want to mark the location with a piece of tape to insure you are observing from the same location each time.