4 Earth’s Motions:1. Axisa. Imaginary line that passes from the north to south pole around which the Earth spins.b. Earth is tilted on its axis at 23.5 degreesc. The North Pole points to Polaris…the North Star.
6 Earth’s Motions: 2. Rotation Day and Night a. The spinning of a planet about its axis. 1 rotation = 1 day = 24 hours.b. The Earth rotates because of inertia- Once it was set in motion, it stays in motionc. ½ the Earth is always in light and ½ is always in darknessDay and Night
7 What evidence tells us that the Earth rotates? 1.Sunset2.Sunrise3. Moon rises and sets4. Shadows change during the day5. Star trails – stars appear to move in the skyMore Star Trails6. Foucault’s pendulum
8 3. What direction does the Earth rotate? Rotating Eartha. Counterclockwise (from west to east)b. *The sun rises in the east and sets in the west.
10 Do Now: In which direction would you look to see the sun rise? In which direction would you look to see the sun set?
11 4. What is the shape of the Earth? a. The Earth is an almost perfect sphere.b. Rapid spinning causes the middle to bulgeand the poles to flatten.c. The diameter of the Earth is 29 miles wider at the equator than at the poles!The diameter from Pole to Pole = 12,714 kmThe equatorial diameter = 12,756 km.
12 How fast does the Earth rotate? That’s 1,038 miles per hour!Why don’t we fly off???a. There are 360 degrees in a sphereb. There are 24 hours in one day.Calculate how many degrees / hour the earth rotates:360 degrees24 hours=15 degrees/hour
13 The Earth at Night… what’s wrong with this picture?
15 5. Earth’s Revolution a. Earth moves around the sun b. It takes about 365 ¼ days for Earth to make one full revolution.c. Causes Earth’s seasons
16 Why do daylight hours change during the year? Earth’s position around the sun causes the sun to be higher or lower in the sky.a. Summer – sun rises higher, takes longer to set, longer daylight hours, shorter shadowsb. Winter – sun rises lower, takes less time to set, shorter daylight hours, longer shadows