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Science – Sun and Earth – Season

Posted on: April 19, 2016

When going through the topic of “Sun, Earth and Moon – Seasons”,  introducing the term “aphelion” and “perihelion” to the girls, showing the picture of the elliptical orbit of the earth, daddy suddenly stopped watching his 《琅琊榜》and asked, “The earth is closest to the sun on the perihelion, furthest on the apehelion. Shouldn’t it be the cause for the seasons we are having on earth?”

And here is a good explanation why it is not.

elliptical_orbit

“If this were the main cause of the seasons,

i. Summer in Tucson would be in January and winter would be in July. 

ii. Summer and winter would both occur at the same times in both hemispheres. 

But neither of these is true. 

The changing distance between the earth and the sun has an effect but is NOT the main cause of seasonal changes.

The main cause of the seasons is the fact that the earth is tilted with respect to its orbit around the sun.”

Let’s watch the below two video:

Now, another question:

What if the earth were not tilted? Do we still have seasons?

 

Reference: http://www.atmo.arizona.edu/students/courselinks/fall07/nats101s31/lecture_notes/oct09.html

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