Download Why do we have seasons?

Why do we have seasons?
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The earth moves around the sun in an elliptical orbit.
Earth is closest to the sun at Perihelion
Earth is farthest from the sun at Aphelion
Is being close to the sun what causes the seasons?
The northern and southern hemisphere should have the same
season, not opposite season like we have.
• No. North Carolina is closest to the sun in the winter!
What makes the difference?
• The more direct the sun’s rays the more
energy in that spot.
• During winter, sun’s rays are more spread
out.
The Reasons for the Seasons on
Earth
• The seasons on Earth are caused by the 23.5º tilt of its
rotation axis, and its revolution around the Sun.
• Although the distance of the Earth to the Sun changes
slightly as it orbits around the Sun, its effect is not big
enough to cause the four seasons.
• The seasons for other planets may be due to the
changing distance to the Sun, not the tilt of their
rotation axis…For example, the orbit of Pluto has a
very large eccentricity.
What is a barycenter?
• The Earth is larger than the moon.
• The barycenter is where they would
balance.
• The Barycenter of the earth/moon is
1710km beneath the Earth’s surface.
Does the sun move?
• The sun wobbles as it is pulled by all of its
planets.
• The sun never strays far from the solar
system barycenter.