1. How does the Earth move in space? What causes the cycle of the seasons on Earth?

2.  Rotation – spins on it’s axis Causes day and night One rotation = 24 hours  Revolution – travels around the sun One revolution = one year (365 ¼ days) Every 4 years is a leap year (366 days) Earth travels in an elliptical (oval) orbit around the sun

3.  Earth is tilted on its axis  Earth has seasons because it is tilted on it’s axis and sunlight hits Earth at different angles  Each hemisphere is tilted toward the sun for part of the year (summer) and away from the sun for part of the year (winter)

4. Earth’s position during the seasons…

5.  Summer solstice (June 21) = Sun is farthest north of the equator in the Northern hemisphere, or farthest south of the equator in the Southern hemisphere (longest day)  Winter solstice (Dec 21)= Sun is farthest south of the equator in the Northern hemisphere, or farthest north of the equator in the Southern hemisphere (shortest day)

6.  Equinoxes occur halfway between solstices  Day and night are both 12 hours long (equal)  Vernal (spring) ~ March 21  Autumnal (fall) ~ Sept. 22