1. Teaching Sample: The Reasons for the Seasons 2003 August 04 Central Arizona College Robert L. Marcialis, Ph.D. 5550 N. Maria Drive Tucson, AZ 85704 (520) 293-7399 umpire@LPL.arizona.edu

2. Discussion: Why do we have seasons?

3. Question: What are the “properties” of Earth’s seasons? Sun’s size stays ~constant throughout year (about 1/2º) Seasons are reversed in Northern, Southern hemispheres Length of daytime, nighttime varies with season “Midnight sun” and days without sunrise near poles Very moderate seasons near the equator: ~constant throughout year

4. To understand true cause, we need to define: ecliptic celestial equator obliquity equinox, solstice

9. For these lecture notes & more, see the course web page: http://www.LPL.arizona.edu/~umpire/CAC/demo.html http://www.LPL.arizona.edu/~umpire/CAC/demo.html