Many people believe that the distances between the sun and Earth are the reason for the seasons. This is not true. There are two causes for the changes of seasons. The inclination of the Earth s axis, or the tilt of the Earth is always the same at 23.5 . This angle does not change as it travels in its orbit around the sun.
Summer occurs when the rays of the sun are the most vertical on a particular place on Earth.
Winter occurs when the sun s rays are the most slanted on a particular place on Earth. Since the rays of the sun are most direct in the tropics all year, the seasonal temperature there change very little except at higher altitudes.