Why Seasons Happen , Misconceptions | English |  Geography, Earth Science, Astronomy
Channel: Arvind Gupta
Date: 2015-06-19

When we think the seasons we realize that amount of heat or energy that we get from the sun changes during the year. If more Energy is received than is lost, our location gets warmer and we have summers; if more energy is lost than is gained, we get cooler and enjoy our winters. 
So what causes the amount of energy reaching a given location to change throughout the year? We asked this question around and got various answers.
First most common response was that:
1. Earth goes around the sun in an ellipse so when we are closer to sun we have summers and winters when we are far. Now even if we consider the path to be ellipse, the whole of earth should have same seasons. Instead when people are sweltering here in peak summer in India, Australians are enjoying cricket in winters. It would also mean that we will have 2 summers and two winters which is not the case.
Actually, sun at the one of the two foci of ellipse and not the center. The closest point of sun to earth is called perihelion and farthest aphelion. The closest to farthest distance changes only by about 3 percent.
In fact the path of earth around the sun is almost a circle 98.4%, eccentricity as 1.6% and so the slight elongation of earth’s orbit doesn’t cause drastic average temperature differences.
The second response we got was that the tilt of the earth leads to seasons because the part tilted towards the Sun is closer than the part tilted away. For this reasoning we have to compare earth’s diameter which is 6400km to earth- Sun distance which is 150 million km. This earth-sun distance is 23500 times larger than the earth’s diameter. So this cannot cause earth to come closer or go farther from sun.

In other words distance from sun or elliptical orbit does not cause seasons

Hope you enjoyed looking at the misconceptions of seasons and in our next video we will look at real reasons behind seasons. This work was supported by IUCAA and Tata Trust. TATA Trust: Education is one of the key focus areas for Tata Trusts, aiming towards enabling access of quality education to the underprivileged population in India. To facilitate quality in teaching and learning of Science education through workshops, capacity building and resource creation, Tata Trusts have been supporting Muktangan Vigyan Shodhika (MVS), IUCAA's Children’s Science Centre, since inception. To know more about other initiatives of Tata Trusts, please visit www.tatatrusts.org