Q. On 21st June, the Sun

  • does not set below the horizon at the Arctic Circle
  • does not set below the horizon at Antarctic Circle
  • shines vertically overhead at noon on the Equator
  • shines vertically overhead at the Tropic of Capricorn

Answer: (a) does not set below the horizon at the Arctic Circle

Notes:

  • Equinox:
    • The whole earth experiences equal days and equal nights over equinox.
    • It occurs on 21st March and September 23rd.
    • At this position, direct rays of the sun fall on the equator. 
    • At this position, neither of the poles is tilted towards the sun i.e shines vertically overhead at noon on the Equator.
  • Winter Solstice:
    • It occurs on the 22nd of December.
    • During the winter solstice, the nights are longer than the days.
    • On 22nd December,  the Tropic of Capricorn is tilted towards the sun and the sun does not set below the horizon at Antarctic Circle.
    • As the sun’s rays fall vertically over the Tropic of Capricorn (23½° S), the Southern Hemisphere receives a major portion of the sun’s light.
  • Summer Solstice:
    • During Summer solstice, the days are longer than the nights. 
    • It occurs on the 21st of June in the northern hemisphere.
    • On 21st June, the tropic of cancer is tilted towards the sun i.e the sun is always above the horizon and does not set below the horizon at the Arctic circle.
    • After the Summer Solstice, the sun starts to sink towards the horizon.
    • As the rays of the sun fall directly on the Tropic of Cancer, the northern hemisphere experience more heat.
Summer Solstice