1. Solar System: Sun, Earth and Moon

2. Earth’s size and shape The earth is sphere.
Aristotle made three observations:
Objects fall straight down
Earth’s shadow is curved
People see different stars

3. Earth

5. Gravity The attractive force between two objects
Depends on the masses and distance between two objects.
How does the pull of gravity indicate that the Earth’s shape is spherical?

6. Earths properties: Diameter Pole to Pole 12,714 km
Diameter through equator
12,756 km
Circumference poles
40,008 km
Circumference equator
Mass
5.98 X 1024 kg
Avg distance from sun
149,600,000km
Avg distance from moon
384,400 km
Period of rotation
23hr 56 min
Period of revolution
365 days, 6h,9min

7. Earth’s magnetic field
Hypothesized that the strong rotation of the earth and the movement in the core set up the magnetic field
The magnetic poles are 11.5* off from the physical poles.
They wander due to the movement of the Earths crust and mantle

8. Magnetic fields

9. Magnetosphere
An area in the Earth’s magnetic field that deflects harmful radiation coming from the sun as solar wind
These collide with atoms in the atmosphere causing the aurora borealis or aurora australis

11. Earth’s Orbit
ellipse

13. Earth Is a planet Supports life
Has lower CO2 than Venus but trapped CO2 may contribute to green house effect
Ocean absorbs CO2

14. If the magnetic field was not there to protect us what would happen to the earth?

15. The Sun and Earth: seasons
The earth moves in two ways:
Rotation: the earth spinning like a top around its axis. 24 hours or one day
Revolution: The earth traveling around the sun. It takes one year 365 ¼ days

16. Rotation of the earth

17. Revolution of the earth

18. Where the sunlight hits the earth
Slanted less intense at an angle
Direct intense light
Slanted less intense at an angle

19. Seasons
Seasons are caused by the tilt of the Earth’s axis as it moves around the sun.
The amount of sunlight depends on the Latitude that the sunlight is directly hitting.

20. Solstices
Solstices occur twice a year on the days that the sun appears directly overhead at latitude north or 23.5 south. Remember the earth tilts 23.5 degrees off of the axis.
Northern Hemisphere: Summer solstice on June 21st. The Northern Hemisphere is tilted toward the sun. The longest day in the North and the shortest in the South.
North- Summer, South-Winter.

22. Solstice
Winter solstice occurs on December 21 six months after the Summer Solstice.
The Northern Hemisphere is tilted away from the sun and receives the least amount of light.
Shortest day in the North and Longest day in the South.
North-Winter, South-Summer

24. Equinoxes Halfway between the solstices are two days called Equinoxes.
See page 754:
Halfway between the solstices are two days called Equinoxes.
At the Equinox neither hemisphere is tilted toward the sun the length of day light and night is EQUAL.
March 22- Spring, September 22- autumn

25. Spring equinox is called Vernal equinox.
Autumn equinox is called the Autumnal equinox.
On these two days the sun is directly overhead the equator.

26. http://www.classzone.com/books/earth_science/ter c/content/visualizations/es0408/es0408page01.cfm

27. Review What two ways does the earth move in space?
What determines the change in seasons?

28. Solar eclipse