1. Earth-- spins on an imaginary center line Earth’s axis.
2. rotation--spinning of Earth on its axis, takes about 24 hours.
3. day/night—caused by rotation
4. Revolution --is Earth’s orbit, or path around the Sun takes one year
5. year—one revolution around the Sun
6. Earth’s orbit --is elliptical (egg shaped), closest to Sun around January 3, and farthest from Sun around July 4.
7. Earth’s tilt-- Earth’s axis is tilted 23.5 degrees
8. tilt—causes Earth to receive different amounts of solar energy from place to place during the year.
9. Northern Hemisphere-- summer begins in June, is tilted toward the Sun.
10. summer-- more hours of sunlight equals solar energy. More solar energy equals more heat.
11. Earth’s tilt-- causes Sun’s radiation to strike the hemispheres at different angles.
12. Summer --happens in hemisphere tilted toward the Sun, radiation strikes Earth at a high angle and for longer periods of time.
13. solstice-- the day when the Sun reaches its greatest distance north or south of the equator.
14. Summer solstice-- longest day of the year, Sun is over Tropic of Cancer.
15. Winter solstice-- shortest day of the year, Sun is over Tropic of Capricorn.
16. Northern Hemisphere—summer equals winter in Southern Hemisphere.
17. Spring and Autumnal Equinox--two times a year the Sun is directly over the equator, neither hemisphere tilted toward Sun, equal daylight/equal night both hemisperes.
18. Spring equinox-- March 20 or 21, Autumnal equinox September 22 or 23.