Unit 1:The World in Spatial Terms

Lesson 9: Earth-Sun Relationship

Earth-Sun Relationship

• It’s the reason for the season• Life on earth is supported by the

Sun’s energy • No sun=no life

What Causes Seasons?

• All parts of the earth do not receive the same amount of sunshine year-round.

• The difference in the amount of sunshine received is the result of two things:

1. Movement of the earth around the sun (365 day rotation).

2.Tilt of the earth on its axis (imaginary line drawn from the North Pole to the South Pole through the center of the earth. (24 hour rotation)

Seasons in the Northern Hemisphere

• Northern Hemisphere-the part of the earth north of the Equator

• Because the earth is tilted, its axis always points in the same direction

• As the earth rotates around the sun, sometimes the N. Pole is pointed at the sun and sometimes away from it

• Summer=the N. Pole is pointed at the sun.= more direct sunrays

• Winter=the N. Pole is pointed away from the sun= more indirect sunrays

• See figure 1-10 on next slide

Figure 1-10: Earth’s Movement Around the Sun

Seasons in the Southern Hemisphere

• When it is summer north of the Equator, it is winter south of the equator