1. Third Rock From the Sun
S6E2- Students will understand the effects of the relative positions of the earth, moon, and sun. c. Relate the tilt of the earth to the distribution of sunlight throughout the year and its effect on climate.

2. Section 1- Earth in Space
Earth , Moon, and Sun- Chp. 15
Section 1- Earth in Space
page 514

3. What is astronomy?
The study of the moon, star, and other objects in space.

4. Ancient Egyptians were some of the first people to study the stars.

5. How does the Earth move?
1. Rotation
2. Revolution

6. Rotation spinning of Earth on its axis causes day and night
24 hours to rotate once
each 24 hour cycle= day
sun appears to set in west

7. Rotation

8. Revolution Earth travels around sun.
movement of one object around another
one revolution= one year
path= orbit of Earth as it revolves
path is not quite circular= elongated = ellipse

9. Revolution

10. The Seasons of the Earth
-Areas outside of the tropics and polar regions have four seasons: summer, fall, winter, and spring

11. Climate Zones
Watch BrainPop Climate Zones

15. Three Climate Zones: Tropical Climate Zone Temperate Climate Zones
Polar Climate Zones
23.50 N o S
(Low Latitudes)
23.5oN oN
23.5oS oS
(Middle Latitudes)
66.33oN - 90oN
66.33oS - 90oS
(High Latitudes)

17. Why do some climate zones have seasons?
Earth has seasons because its axis is tilted as it revolves around the sun.

18. Four Seasons

21. Earth in June- Northern Hemisphere
-North end of Earth’s axis is tilted toward sun
-In Northern Hemisphere, the noon sun is high in sky = more hours of sunlight than darkness
-Direct rays + more hours of sunlight=
Summer!

23. Earth in June- Southern Hemisphere
-Sun’s energy is spread over a larger area.
-Sun is low in sky and days are shorter.
-Less direct sun rays and fewer hours of sunlight heats Earth’s surface less= Winter!

25. Earth in December Northern Hemisphere
Sun’s rays are slanted and few hours of daylight= WINTER!
Southern Hemisphere
Receives the most direct sunlight = SUMMER!

26. Solstices
Sun reaches its greatest distance north or south of the equator twice each year.

27. Solstice- day when the sun is farthest north of the equator
Summer Solstice
Northern Hemisphere
Longest Day
Around June 21
Winter Solstice
Southern Hemisphere
Shortest Day
Around June 21

28. Solstice- the day is farthest south of the equator
Winter Solstice
Northern Hemisphere
Shortest Day
Around Dec. 21
Summer Solstice
Southern Hemisphere
Longest Day
Around Dec. 21

29. Equinox- “equal night”
Halfway between the solstices, neither hemisphere is tilted toward or away from sun.
Occurs twice a year when noon sun is directly overhead at the equator.
Day and night are each 12 hours long.

30. Equinoxes Vernal Equinox Spring March 21
Marks beginning of spring in Northern Hemisphere
Autumnal Equinox
Fall
September 21
Marks
beginning of fall in Southern Hemisphere