 Earth moves in 2 ways: Rotation (spinning of the Earth’s axis) and Revolution (Movement of one body in space around another)  Earth’s rotation causes day/night, as Earth rotates from west-east, the sun appears to move from east-west  As Earth continues to spin toward the east, the sun sets in the west and night falls

 As Earth rotates on its axis, it also travels around the sun  It takes about 365 ¼ days to complete a full revolution around the sun (Called an Earth year)

 Different parts of the Earth receive different amounts of sunlight depending on their latitude (measures distance in degrees north or south of the equator)  Regions near the equator receive more sunlight than the poles

 Scientists use lines of latitude to mark out 3 different types of regions within which temperature are generally similar (tropic, temperate, polar zones)  23.5° south-23.5° north =tropic zone  23.5° north-66.5°north and from 23.5° south- 66.5° south=temperate zones  66.5° north-North Pole and from 66.5° south- South Pole=polar zones

 Most of the United States is in the temperate zone  What causes the seasonal changes? The seasons are caused by the tilt in the Earth’s axis as it moves around the sun (Earth tilted 23.5°)

 Because the tilt in the Earth’s axis, the latitude at which the noon sun appears directly overhead changes each day  A solstice occurs on 2 days each year when the sun is directly overhead at latitude 23.5° north or 23.5° south

 In the northern hemisphere the summer solstice begins around June 21 st (start of summer, tilted towards sun, daylight hours longer)  In the northern hemisphere 6 months later on about December 21 st the winter solstice marks the beginning of winter (tilted away from sun, daylight hours shorter)  Seasons affected by the tilt of the Earth not where it is in its orbit

 Marks the beginning or spring and autumn (halfway between the solstices)  At an equinox neither hemisphere is tilted toward the sun, and the lengths of the days/nights are equal  The vernal equinox which occurs about March 21 st in the northern hemisphere marks the start of spring  The autumnal equinox which occurs about September 22 nd in the northern hemisphere marks the star of autumn (Noon sun is directly overhead at the equator)