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What determines the length of a day?
The spinning of a Planet on its axis is called a rotation
Earth rotates on its axis at about 1668 km/hour.
A person can rotate by standing in one place and turning around and around.
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Rotate
Earth spinning on it’s axis gives us day and night
Rotating
Only one half of the Earth faces the sun at any given time
When Earth is facing the sun, it is daytime, when Earth is facing away from the sun, it is night time
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Day vs. Night
Earth completes one rotation on its axis in 24 hours, or one day
Full rotation
What determines the length of a year?
As Earth rotates on its axis, it also revolves or orbits around the sun
Rotate and Revolve
Go around something else
Satellites, the space shuttle, space stations, and the Moon all orbit (go around) the Earth.
The earth and all the other planets revolve around the sun.
Caused by the gravitational pull of another object
Orbit/Revolve
Earth makes an orbit around the sun.
Every 365.25 days (12 months or one year) earth makes a full revolution (or full orbit) around the sun.
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Revolution and Orbit
http://sciencenetlinks.com/interactives/messenger/or/OrbitRotation.html
Rotate and Orbit
The Tilt of the Earth’s Axis
The earth is titled on its axis at 23.5° and it is always pointing in the same direction
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Earth’s Axis
The Earth experiences longer periods of day light when facing the sun
The Earth’s tilt and the orbiting of the Earth around the Sun causes the seasons.
Seasons
When the North Pole is tilted toward the sun, the sun’s rays strike the Northern Hemisphere MORE directly, and this region is warmer
When the South Pole is tilted toward the sun, the sun’s rays strike the Southern Hemisphere LESS directly, and this region is colder
https://www.youtube.com/watch?v=9n04SEzuvXo
Near the equator sun rays hit Earth’s surface MORE directly, so temperatures are warmer there
Near the poles, the sun rays hit the Earth’s surface LESS directly, so the temperatures are colder there
Equator and the Poles
At Equator = 12 hours of day light
Toward sun = more than 12 hours of day light
Away from sun = less than 12 hours of day light
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Hours of Light and Darkness
Mr. Parr: Earth orbit: https://www.youtube.com/watch?v=YONrbl6xLIM
Space Rap: http://www.flocabulary.com/solar-system
