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Sun at Rising and Setting is oval in shape

Updated on May 6, 2012



The shape of the disc of the sun or full moon at rising or at setting is oval (elliptical)

Light from the sun or moon after travelling through vacuum enters into our atmosphere. As light passes from a rarer medium to a denser one, its course is deviated towards the common normal. This deviation of light is called Astronomical refraction.

This effect is maximum at the time of rising or setting of the sun or moon. But this effect of refraction is more on the horizontal diameter (=D(1-k)) than the vertical diameter (=D(1-k sec2z)). So the shape of the sun or full moon at rising or at setting is oval.


The summer season is longer than the winter.

The seasons occur due to the two causes namely, the revolution of the earth around the sun and the constant inclination of earth’s axis to its orbit.

The actual orbit of the earth around the sun is an ellipse with the sun at a focus. So the apparent orbit of the sun around the earth is an equal ellipse with the earth at a focus.

Assuming the earth is at rest, the apparent positions of the sun in different dates during a year is given below:



It is found that the lengths of the spring, summer, autumn and winter seasons are respectively 92 days 20.2 hours, 93 days 14.4 hours, 89 days 18.7 hours and 89 days 0.5 hours. Therefore, for a place situated above the equator, the summer season is longer than the winter.

The longest day of the year is NOT the hottest day . . . in the next hub!


The rising sun
The rising sun

Sunset at Cochin


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