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In the northern hemisphere, the winter solstice usually falls on December 21/December 22, which is the southern hemisphere's summer solstice. At this time, the Sun appears over the Tropic of Capricorn, roughly 23.5 degrees South of the earth's equator. In the southern hemisphere, winter solstice falls on June 21/June 22, which is the northern hemisphere's summer solstice. At this time, the Sun appears over the Tropic of Cancer.
Since the winter solstice, summer solstice, vernal equinox, and autumnal equinox were probably observed for the first time by people in the northern hemisphere, these naming conventions originally corresponded to the northern hemisphere's seasons. In most reckonings, the winter solstice is midwinter. In Ireland's calendar, the solstices and equinoxes all occur at about midpoint in each season. For example, winter begins on November 1, and ends on January 31. The passage and chamber of Newgrange, a tomb in Ireland, are illuminated by the winter solstice sunrise. A shaft of sunlight shines through the roof box over the entrance and penetrates the passage to light up the chamber. The dramatic event lasts for 17 minutes at dawn from the 19th to the 23rd of December.
The winter solstice is the time when the Germanic festival of Yule was celebrated; it is celebrated today as a Neopagan Sabbat. Many cultures celebrate or celebrated a holiday near (within a few days) the winter solstice; examples of these include Yalda, Saturnalia, Christmas, Karachun, Hanukkah, and Kwanzaa. (See also List of winter festivals). The first civilization to celebrate the winter solstice were the Ancient Persians, deriving from their Zorastorian religion.
Through an interesting coincidence in the Earth's orbit, the northern hemisphere's winter occurs when the sun is actually closest to the earth. Conversely, the northern summer is when the sun is farthest from the earth. But the distance from the sun doesn't affect the seasons on Earth to a measurable amount, since Earth's eliptical orbit is the closest to circular of all of the planets in the solar system. In general it's the angle of the sun's rays and the number of hours of light per day that actually affects the seasons in most regions on the planet.
