|UTC Date and Time of solstices and equinoxes|
A solstice is an astronomical event that happens twice each year when the Sun reaches its highest position in the sky as seen from the North or South Pole. The day of the solstice is either the "longest day of the year" or the "shortest day of the year" for any place on Earth, because the length of time between sunrise and sunset on that day is the yearly maximum or minimum for that place. The name is derived from the Latin words sol (“sun”) and sistere (“to stand still”). During the solstice, the Sun stands still; that is, the seasonal movement of the Sun's path comes to a stop before reversing direction. The “Northern Solstice” occurs in June, when the sun is at its highest point seen from the North Pole. The “Southern Solstice” occurs in December, when the sun is at its highest point seen from the South Pole.
The June Solstice happens when the Northern Hemisphere of the Earth is tilted toward the Sun and the Southern Hemisphere of the Earth is tilted away from the Sun. At the North Pole, the Sun reaches its highest point in the sky, and then begins moving lower. At the moment of the June solstice, the Sun is directly overhead some point on the Tropic of Cancer; this is the furthest north that the subsolar point ever reaches. In the Northern Hemisphere the June solstice is called the Summer Solstice (and marks the longest day of the year), while in the Southern Hemisphere it is called the Winter Solstice (and marks the shortest day of the year). The June Solstice is usually on June 21.
The December Solstice happens when the Southern Hemisphere of the Earth is tilted toward the Sun and the Northern Hemisphere of the Earth is tilted away from the Sun. At the South Pole, the Sun reaches its highest point in the sky, and then begins moving lower. At the moment of the December solstice, the Sun is directly overhead some point on the Tropic of Capricorn; this is the furthest south that the subsolar point ever reaches. In the Southern Hemisphere the December solstice is called the Summer Solstice (and marks the longest day of the year), while in the Northern Hemisphere it is called the Winter Solstice (and marks the shortest day of the year). The December Solstice is usually on December 21.
While the exact causes were long unknown, the effect (of days getting shorter or longer) was recognised in many ancient cultures. Many of the pre-Christian cultures, like the druidic, the Germanic and the Norse faith therefore celebrated these events as holidays.
When the importance of the old faiths vanished, the Christian religion took over some of the festivities, which were then carried out in the honour of a new (Christian) occasion. For instance, the date of Christmas in the Catholic and Protestant faith is just 3 days away from the December Solstice.
- "A Solargraph taken from APEX at Chajnantor". European Southern Observatory. Retrieved 2011-12-25.