1. The Effects of the Rotation of the Earth
As Earth Rotates:
The Effects of the Rotation of the Earth

2. What is Astronomy?
Astronomy is the scientific study of matter in outer space.
It is known as the 1st science because of written astronomical observations by the Babylonians around 1600 B.C.

3. Earth, Moon, and Sun: The Moon revolves around the Earth.
The Earth revolves around the Sun.

4. Earth’s Orbit:
Earth’s orbit (path) around the Sun is NOT a perfect circle.
Earth’s orbit is an elongated circle, or an ellipse.

5. Earth’s Revolution:
It takes Earth 365 ¼ days to complete one revolution around the Sun = year.

6. Earth’s Orbit

7. Earth’s Axis:
Earth’s axis is an imaginary line through the center of the Earth from the North Pole to the South Pole.
Earth’s axis is tilted 23.5°

8. Earth’s Axis

9. Earth’s Rotation:
Every 24 hours, Earth rotates, or turns around its axis.
One complete turn of Earth is called a rotation = 1 day.

10. Earth’s Rotation:
Earth’s rotation is what causes day and night.

11. Planet
Revolution
Rotation
Mercury
88 days
58 days
Venus
224 days
243 days
Earth
365 days
24 hours
Mars
687 days
24.6 hours
Jupiter
12 years
10 hours
Saturn
29 years
Uranus
84 years
18 hours
Neptune
165 years
19 hours
*Pluto
248 years
6 days

12. Reason for the Seasons:
Earth has seasons because its axis is tilted as it revolves around the Sun.

13. Earth’s Tilt and Seasons:
Earth’s tilt puts part of Earth into the Sun’s rays at a more direct angle than other parts.

14. Earth’s Tilt and Seasons:
When a part of Earth tilts toward the Sun, the Sun is higher in the sky and its rays hit that section at a higher angle = rays are closer together = more effective at heating Earth.

15. Earth’s Tilt and Seasons:
In June, the Northern Hemisphere of the Earth (where we live) is tilted toward the Sun = summer.
The Southern Hemisphere = winter.

16. Earth’s Tilt and Seasons:
In December, the Northern Hemisphere of the Earth is tilted away from the Sun = winter.
The Southern Hemisphere = summer.

18. Earth’s Tilt and Daylight:
The tilt of the Earth affects the length of daylight.
Higher Sun = more daylight = more time for Sun’s rays to heat Earth.

19. Summer Solstice:
Around June 21st is the longest day and highest angle of sunlight.
It is known as the summer solstice.

20. Winter Solstice:
Around December 21st is the shortest day and lowest angle of sunlight.
It is known as the winter solstice.

22. Equinox: Happens twice a year on first days of spring and fall.
Sun directly above equator and equal hours of daylight and night (12 hours).