ICSE Class 9 Answered

The solstices and equinoxes are caused due to the position of the Earth with respect to the Sun during fixed days. The seasons change on the Earth due to its revolution around the Sun.

• On March 21 and September 23, the sun’s rays are directly above the Equator. On these two days, the days and the nights are of equal duration, i.e. of twelve hours each. This is known as equinoxes.

   

• On June 21, the Northern Hemisphere is tilted towards the Sun. Since the direct rays of the Sun fall on the Tropic of Cancer, these areas receive more heat. The areas near the poles get slanting rays of the sun and thus they receive less heat of the Sun. Since the greater part of the Northern Hemisphere receives light from the Sun, it is the summer season in places lying to the north of the Equator (Northern Hemisphere).

   

• On June 21, the day is longest and the night is shortest in the Northern Hemisphere.

   

• The conditions are reversed at the Southern Hemisphere as it is tilted away from the Sun. The Sun’s rays do not reach the South Polar Regions beyond the Antarctic Circle. This marks the winter season in South Hemisphere.

   

• This is called summer solstice.

   

• On December 22, the Sun is directly above the Tropic of Capricorn. Since the South Pole is inclined towards the Sun, it is the summer season in places lying south of the Equator (southern hemisphere).

   

• The conditions are reversed in the North Pole. Since it is tilted away from the Sun, it is the winter season. 22 December has the longest night and the shortest day in the Northern Hemisphere. It is known as the winter solstice.

   

• On September 23, the Sun is vertically overhead the Equator. The days and nights are of equal duration at the Equator. It is autumn in the Northern Hemisphere and hence it is called as Autumnal Equinox. It is the spring season in the Southern Hemisphere at this time.
• On March 21, it is the spring season in the Northern hemisphere and hence it is known as the Vernal Equinox.