Days, Years & Seasons

Days and Nights

Rotation: the Earth turns around on its axis1 day=24 hours (one rotation)One half of the Earth is always in light and one half is always in darknessList some examples of rotation…

Years

Revolution: the Earth moves around the sun1 year=365 1/4 days (one revolution)List some examples of revolutions…

What REALLY causes the seasons?

The Earth is tilted as it revolves around the sun.

Seasons (summer, fall, winter, spring)

The Earth’s axis is tilted 23 1/2 degrees from verticalThe tilt is always oriented the same way and causes the four seasonsThe 23 1/2 degree tilt causes the sunlight to follow a different path across the Earth’s surface

Summer Solstice: June 21

The Earth’s Northern Hemisphere is tilted towards the sun

Summer Solstice

More direct energy (heat) enters the atmosphereThere is 24 hours of daylight at the North Pole and 24 hours of darkness at the South PoleThe longest day of the yearAphelion: the Earth is the farthest from the sun (94 million miles)

Winter Solstice: December 21

The Earth’s Northern Hemisphere is tilted away from the sun

Winter Solstice

The sun’s energy (heat) is more concentrated in the Southern HemisphereThere is 24 hours of daylight at the South Pole and 24 hours of darkness at the North PoleThe shortest day of the yearPerihelion: the Earth is the closest to the sun (91 million miles)

What happens when the Earth is not tilted toward or away

from the sun?HERE

And… HERE

EquinoxThe Earth is not tilted toward or away from the sunSpring Equinox: March 21Fall Equinox: September 21There are 12 hours of daylight and 12 hours of darkness from the North Pole to the South PoleThe distance between the sun and the Northern and Southern Hemispheres of Earth are equal!

Seasons Animations

http://www1.teachertube.com/viewVideo.php?title=What_Causes_Seasons_on_Earth&video_id=657

http://esminfo.prenhall.com/science/geoanimations/animations/01_EarthSun_E2.html