How does our journey through space cause days, years, and seasons? As the World Turns How does our journey through space cause days, years, and seasons?

Rotation Earth rotates on its axis once every 24 hours. We call this one day. When your part of the earth faces the sun, you experience day. What happens to cause night?

East West Sun appears to rise in the east and set in the west because the Earth turns on its axis from west to east.

Revolution The path the Earth takes around the sun is called it’s revolution. It takes us 365.24 days to travel around the sun. We revolve around the sun counterclockwise. http://members.shaw.ca/len92/earth_revolution.gif

Moving through Space The Earth revolves around the Sun at a rate of about 67,000 miles per hour We are also moving through space with our solar system and the Milky Way Galaxy We don’t feel how fast we are moving because we have no way to sense the movement

Seasons Are caused by the tilt of the Earth’s axis, which is at an angle of 23.5 degrees Each season lasts 3 months Equator is the line that divides the Northern and Southern Hemispheres The hemisphere tilted toward the sun gets more direct light There are four special times during the year.

+ Solstices Summer Solstice – sun’s rays hit as far north as the tilt will allow – occurs in the month of June Winter Solstice – sun’s rays hit as far south as the tilt will allow – occurs in the month of December

Observing Solstices The Summer and Winter Solstices have been important to mankind for a long time. Stonehenge is aligned to measure the solstices.

Equinoxes Vernal Equinox in March and the Autumnal Equinox in September; Equinox means “equal night”. These were considered the two days of the year where daylight and nigh time hours were equal. Now refers to the days the center of the sun is directly above the equator.

Many people believe we have summer because we are closer to the sun in the summer. Look at the diagram and explain why they are wrong!

Questions?