Solstices and Equinoxes

Heavens Above
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The June and December solstices mark the longest and shortest days of the year. The March and September equinoxes, meanwhile, mark the two days of each year when day and night are of equal length.

June Solstice (Approximately June 20-21)

The June solstice begins summer in the Northern Hemisphere and winter in the Southern Hemisphere. This day is the longest of the year in the Northern Hemisphere and the shortest of the year in the Southern Hemisphere.

  • North Pole: The North Pole (90 degrees north latitude) receives 24 hours of daylight, as it has been daylight at the North Pole for the last three months (since the March Equinox). The sun is 66.5 degrees off the zenith or 23.5 degrees above the horizon.
  • Arctic Circle: It is light 24 hours a day north of the Arctic Circle (66.5 degrees north) on the June solstice. The sun at noon is 43 degrees off the zenith.
  • Tropic of Cancer: On the June Solstice the sun is directly overhead the Tropic of Cancer (23.5 degrees north latitude) at noon.
  • Equator: At the equator (zero degrees latitude), the day is always 12 hours long. At the equator, the sun rises daily at 6 a.m. local time and sets at 6 p.m. local time. The sun at noon at the equator is 23.5 degrees off the zenith.
  • Tropic of Capricorn: In the Tropic of Capricorn, the sun is low in the sky, at 47 degrees from the zenith (23.5 plus 23.5).
  • Antarctic Circle: At the Antarctic Circle (66.5 degrees south), the sun makes the briefest of appearances at noon, peeking at the horizon and then instantaneously disappearing. All areas south of the Antarctic Circle are dark on the June Solstice.
  • South Pole: By June 21, it has been dark for three months at the South Pole (90 degrees south latitude).

September Equinox (Approximately September 22-23)

The September equinox marks the beginning of fall in the Northern Hemisphere and spring in the Southern Hemisphere. There are 12 hours of daylight and 12 hours of darkness at all points on the earth’s surface on the two equinoxes. Sunrise is at 6 a.m. and sunset is at 6 p.m. local (solar) time for most points on the earth’s surface.

  • North Pole: The sun is on the horizon at the North Pole on the September equinox in the morning. The sun sets at the North Pole at noon on the September equinox and the North Pole remains dark until the March equinox.
  • Arctic Circle: Experiences 12 hours of daylight and 12 hours of darkness. The sun is 66.5 degrees off the zenith or 23.5 degrees above the horizon.
  • Tropic of Cancer: Experiences 12 hours of daylight and 12 hours of darkness. The sun is 23.5 degrees off the zenith.
  • Equator: The sun is directly overhead the equator at noon on the equinox. On both equinoxes, the sun is directly over the equator at noon.
  • Tropic of Capricorn: Experiences 12 hours of daylight and 12 hours of darkness. The sun is 23.5 degrees off the zenith.
  • Antarctic Circle: Experiences 12 hours of daylight and 12 hours of darkness.
  • South Pole: The sun rises at the South Pole after the Pole has been dark for the past six months (since the March equinox). The sun rises to the horizon and it remains light at the South Pole for six months. Each day, the sun appears to rotate around the South Pole at the same declination angle in the sky.

December Solstice (Approximately December 21-22)

The December solstice marks the beginning of summer in the Southern Hemisphere and is the longest day of the year in the Southern Hemisphere. It marks the beginning of winter in the Northern Hemisphere and is the shortest day of the year in the Northern Hemisphere.

  • North Pole: At the North Pole, it has been dark for three months (since the September equinox). It remains dark for another three (until the March equinox).
  • Arctic Circle: The sun makes the briefest of appearances at noon, peeking at the horizon and then instantaneously disappearing. All areas north of the Arctic Circle are dark on the December solstice.
  • Tropic of Cancer: The sun is low in the sky, at 47 degrees from the zenith (23.5 plus 23.5) at noon.
  • Equator: The sun is 23.5 degrees from the zenith at noon.
  • Tropic of Capricorn: The sun is directly overhead the Tropic of Capricorn on the December solstice.
  • Antarctic Circle: It is light 24 hours a day south of the Antarctic Circle (66.5 degrees north) on the June solstice. The sun at noon is 47 off the zenith.
  • South Pole: The South Pole (90 degrees south latitude) receives 24 hours of daylight, as it has been daylight at the South Pole for the last three months (since the September equinox). The sun is 66.5 degrees off the zenith or 23.5 degrees above the horizon. It will remain light at the South Pole for another three months.

March Equinox (Approximately March 20-21)

The March equinox marks the beginning of fall in the Southern Hemisphere and spring in the Northern Hemisphere. There are 12 hours of daylight and 12 hours of darkness at all points on the earth’s surface during the two equinoxes. Sunrise is at 6 a.m. and sunset is at 6 p.m. local (solar) time for most points on the earth’s surface.

  • North Pole: The sun is on the horizon at the North Pole on the March equinox. The sun rises at the North Pole at noon to the horizon on the March equinox and the North Pole remains light until the September equinox.
  • Arctic Circle: Experiences 12 hours of daylight and 12 hours of darkness. The sun is 66.5 off the zenith and low in the sky at 23.5 degrees above the horizon.
  • Tropic of Cancer: Experiences 12 hours of daylight and 12 hours of darkness. The sun is 23.5 degrees off the zenith.
  • Equator: The sun is directly overhead the equator at noon on the equinox. During both equinoxes, the sun is directly over the equator at noon.
  • Tropic of Capricorn: Experiences 12 hours of daylight and 12 hours of darkness. The sun is 23.5 degrees off the zenith.
  • Antarctic Circle: Experiences 12 hours of daylight and 12 hours of darkness.
  • South Pole: The sun sets at the South Pole at noon after the Pole has been light for the past six months (since the September equinox). The day begins on the horizon in the morning and by the end of the day, the sun has set.