STUDY of the EARTH’s Movements

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STUDY of the EARTH’s Movements. 6 th Grade Science . What is mathematical shape is the Earth? . Sphere. What does it mean when an object is a sphere? . Sphere : a round, 3-dimensional object . Its surface is the same distance from its center at all points .

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### STUDY of the EARTH’s Movements

Sphere
• What does it mean when an object is a sphere?
Sphere: a round, 3-dimensional object
• Its surface is the same distance from its center at all points
Aristotle –around 350 B.C.
• Believed that the Earth was a perfect sphere and that all planets orbited around it
*Besides Aristotle, many other individuals suspected that the Earth was round. *How did they start suspecting this?
Sailors noticed that in approaching ships, the tops of ships came across the horizon and appeared first
No!
• ItBULGESslightly at the equator
• It is FLATTENEDat the poles
• Not a PERFECT sphere
Earth’s Rotation
• Rotation: the action of spinning around an axis or center
Earth’s Rotation
• How does the Earth’s rotation cause day and night?
As the Earth rotates, part of the Earth faces away from the Sun, and faces dark outer space. This is what causes day and night.
You can’t feel the Earth’s rotation, but standing on top of the Earth is like riding a giant spinning top

During night, your area of the Earth has rotated so that it is on the opposite side of the Sun *We can’t see the Sun anymore, but the Sun is still lighting up the moon.

The tilt of Earth’s axis causes the seasons! It causes the seasons as it is revolvingaround the Sun
• Remember that the Earth revolves or orbits the Sun in the shape of an ellipse
The Sun shines more brightly on either the Northern and Southern hemisphere depending on the season
• Earth’s axial tilt causes the Sun’s radiation to strike the hemispheres at different angles
• In Summer, the Northern Hemisphere is tilted toward the sun, so it is getting more direct sunlight

During winter in North America, the Sun is still shining, but because of axial tilt, North America is facing away from it and not getting very much light.

Daylight hours are longer for the hemisphere that is tilted toward the Sun because that hemisphere has more exposure to light for a longer period of time

Equinox: occurs 2 times per year
• During an equinox, the number of daylight hours and nighttime hours is nearly equal all over the world
• Northern Hemisphere: The Sun reaches the spring equinox on March 20-21, and the fall equinox occurs on September 22-23
A Solstice is when the Sun is at its greatest distance from hitting the equator
• Summer solstice in the Northern Hemisphere = June 21  longest day of the year
• Winter solstice in the Northern Hemisphere = December 21  shortest day of the year
365 ¼ days
• 4 Seasons