1. Seasons, Tides, and Phases of the Moon J. C. Sprott Department of Physics University of Wisconsin Madison, WI 53706 Presented to the Green County Science Teachers’ Workshop on February 25, 2000

2. Science Literacy n Over 200 studies document scientific illiteracy. n Scientific illiteracy hurts Nation and individuals. n Teachers are uncomfortable teaching science. n Science has fallen out of favor. n We have a public-relations problem.

3. What causes the seasons? EarthSun

4. How many times does the earth rotate about its axis in a year? Earth Sun 365.242 + 1 = 366.242

5. As seen from the North Pole, which direction does the earth rotate? Earth Sun Counter-clockwise

6. How do we know the earth is rotating? n Foucault Pendulum (1851) n Coriolis Effect u Wind Patterns u Projectile Deflection

7. How do we know the earth orbits the sun? n Annual Parallax of the Stars (1837) - nearby stars appear to move n Aberration of Starlight (1727) - change in apparent direction of stars, cf: raindrops

8. What causes the phases of the moon? Moon Earth Sun

9. When you observe a crescent moon in the evening, do the tips point left or right? West Facing South sun

10. Can a full moon rise at midnight? Earth Sun Full Moon New Moon Half Moon No!

11. Half Moon Sun How can you tell the moon is close and the sun is far? Earth Sun Moon

12. On the scale of the earth as a 10” globe, how far is the moon, sun, etc.? Moon: 25 feet Sun:1.9 miles Pluto:73 miles Alpha Centauri:500,000 miles Space Shuttle:0.25 inch

13. What causes an eclipse? Earth Sun Lunar Eclipse Solar Eclipse

14. Why do we always see the same face of the moon? Moon Earth

15. What causes the tides? Earth Sun Moon

16. Where is the center-of- mass of the earth+moon? Earth Moon R = 0.75R e

17. Where is the center-of- mass of the sun+earth? Sun Earth R = 0.0006R s

18. What does the orbit of the moon around the sun look like? Sun Moon