Seasons Tides and Phases of the Moon J

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

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

What causes the seasons? Earth Sun

How many times does the earth rotate about its axis in a year? 365. 242 + 1 = 366. 242 Sun Earth

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

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

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

Sun What causes the phases of the moon? Earth Moon

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

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

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

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

Sun What causes an eclipse? Solar Eclipse Earth Lunar Eclipse

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

Sun What causes the tides? Moon Earth Moon

Where is the center-ofmass of the earth+moon? Moon R = 0. 75 R e Earth

Where is the center-ofmass of the sun+earth? Earth R = 0. 0006 R s Sun

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