Cycles in the Sky

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3

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A Perfect Day

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Solar Eclipse

August 11, 1999

Soissons, France

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March 29, 2006

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1882 Transit

(USNO)

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Application to Exo Planet Studies

HD 209458 (mv = +7.7) in Pegasus

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Solar Eclipse Activity

GOALS: To simulate a solar eclipse To understand the concept of angular size To make estimates of absolute and

relative size

MATERIALS: Yard or meter stick (don't

confuse your units!) Construction paper Tape Scissors CD-ROM Pencil Black and yellow markers

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PROCEDURE:

1. MAKE THE SUN: Lay the CD on the construction paper and trace around its outer edge. Then trace around the center hole.

2. Draw two lines (a tab) down from the CD and fanning out so the CD circle and tab look like the picture on this slide. The tab will be used to mount the CD circle on the yard/meter stick. 3. Cut out the large CD circle and connected tab. This will represent the sun. The small circle in the center will represent the size of the moon (of course, this is not to scale).

4. Color the CD circle yellow (for the sun) and the small center circle black. 5. MAKE THE MOON: Now, on a different piece of construction paper, trace just the center hole in the CD. Make the same kind of tab for this circle as you did for the sun circle. Make the tab a bit longer than the sun's tab. Color the moon black and cut it out.

6. ASSEMBLE: Bend the sun and moon back 90 degrees from their tabs at the BASE of the tab. Wrap the fanned out portion of the tabs around the yard/meter stick and tape the ends together. The sun should be near the end of the stick and the moon should be near the front. The sun and moon should now be able to slide up and down the stick.