WHAT CAUSES THE SEASONS ?

The changing seasons occur because the earth, tilted on its axis, orbits the sun . Thus, the plane of the equator is tilted with respect to the plane of the earth's orbit. since, the earth is tilted in the same direction, the latitude which the sun appears directly over the head at noon changes as the earth orbits the sun.



The sun follows a yearly pattern of northward and southward motion. If the equatorial plane and orbital plane were the same then the sun would be always overhead to observer at equator and the seasons does not change however, since the planes are tilted about 23 degrees and 30 minutes from each other, the latitude where the sun is found overhead varies throughout the year .

The astronomers divided the year into seasons according to equinoxes and solstices. Equinoxes occur when the earth reaches to the points of the orbit. when the equinoxes and orbits intersects it is noon. During the equinoxes the day time and the night time will be nearly equal. One equinox occur about march 21. in northern hemisphere it is spring, in the southern hemisphere it is autumnal. The other equinox which occurs around September 23, it is autumnal in northern hemisphere and spring in southern hemisphere.

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