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What Causes Seasons on Earth?

-- | May 2, 2013

Question: Hi am just curious about something and I need your help. So well all know it has different seasons in the year, but the thing am curious about it why does the climate change?. What I mean is it gets as high as 40 degree cel int the summer and -40 in the winter. So what I want to know is does the earth or the moon shift away or shift in some way during this time? — Curtnell

Answer: The seasons on Earth are caused by the fact that the rotation axis of the Earth is tilted by 23.5 degrees relative to the plane of our orbit around the Sun. This means that when the northern hemisphere of the Earth is tilted towards to the Sun, the rays from the Sun shine directly on the northern hemisphere, and also the days are correspondingly longer. We call this summer. Six months later, when the Earth is on the other side of its orbit, the rays from the Sun shine on the northern hemisphere at a more oblique (i.e. from a low elevation) angle. This results in shorter days and less direct sunlight shining on the northern hemisphere, which we call winter. See the New Mexico State University Astronomy web site description of seasons for a nice description, with informative pictures, describing what causes seasons on Earth.

Jeff Mangum

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