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Summer happens in the hemisphere tilted towards the Sun, and winter happens in the hemisphere tilted away from the Sun.
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Earth's Tilt Is the Reason for the Seasons!

During the year, the seasons change from winter to spring to summer to fall. Why does it happen? Seasons depend on the Sun!

The seasons happen as the Earth, travels in a loop around the Sun each year. Each year the Earth makes one trip around the Sun. Because the Earth is tilted on its axis, summer happens in the part of the Earth tilted towards the Sun, and winter happens in the part of the Earth tilted away from the Sun. As the Earth travels around the Sun, the part of the Earth that is tilted towards or away from the Sun changes.

The part of the Earth that is tilted towards the Sun is warmer because sunlight travels more directly to the Earth’s surface and less gets scattered in the atmosphere. That means that when it is summer in the northern half of the Earth (the Northern Hemisphere), it is winter in the southern half of the Earth (the Southern Hemisphere). The hemisphere tilted towards the Sun has longer days and shorter nights.

Last modified October 31, 2006 by Travis Metcalfe.

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The Winter 2009 issue of The Earth Scientist, focuses on Earth System science, including articles on student inquiry, differentiated instruction, geomorphic concepts, the rock cycle, and much more!

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