1. Earth – Sun System
Seasons

2. Earth – Sun Relationship
A circle, when viewed from the side, describes a plane.
The plane on which Earth orbits the sun is called the ecliptic.
Earth is tilted on its axis, 23.5 degrees.
Earth’s tilt on its axis and revolution around the Sun are the causes of seasons.

3. Earth on the ecliptic
Draw this axis

4. Rotation Rotation = Spinning Earth’s rotation on its axis = 1 day
The sun appears to rise in the East and set in the West because of Earth’s rotation.
Earth’s rotation is the reason for day and night.

5. Revolution Revolution = Orbiting
Earth’s revolution around the Sun = 1 year ( days)
When Earth is closest to the Sun, it is the perihelion; when farthest from the Sun it is the aphelion.
The length of days (amount of sunlight) and temperatures vary because of our orbit around the sun.
During our revolution, the Sun appears to change its height in the sky; it appears higher in the sky in the summer than in winter.

6. Seasons

7. Spring , also called Vernal Equinox
Sunlight shines directly on the equator
First day is usually ~ March 21
3/21 is my husband and was my Grandma’s b’day!

8. Summer, also called Summer Solstice
Sunlight shines directly on the Tropic of Cancer (23.5 N latitude)
First day is usually ~ June 21 (longest day of the year)
6/21 was my Grandparents’ Anniversary!

9. Fall, also called Autumnal Equinox
Sunlight shines directly on the equator
First day is usually ~ September 21
9/21 was also my Grandaddy’s b’day!

10. Winter, also called Winter Solstice
Sunlight shines directly on the Tropic of Capricorn (23.5 S Latitude)
First day is usually ~ December 21 (shortest day of the year)
My Mom’s b’day is Dec. 22!

11. Earth’s Position in the Sky
Draw this diagram! (make sure to get the axis right at each position!)