Day is the length of time between sunrise and sunset when the sun is visible above the horizon. Daylight hours can have different longitudes, depending on the latitude of the place and on the angle of declination of the star.
The length of the day depends on the daily rotation of the Earth around its axis and the orbital rotation around the Sun. Due to the Earth's orbit, the solar disk makes an annual visible round of the celestial sphere, moving along the ecliptic. In this regard, its declination changes and affects the longitude of the day in different ways at different geographic latitudes.
At the Earth's equator, daylight hours are approximately constant at about 12 hours. In the northern hemisphere of the Earth, from March to September, daylight hours are more than 12 hours, and from the end of September to the end of March - less. In the Southern Hemisphere, everything is exactly the opposite. In the Arctic Circle, daylight hours can be longer than 24 hours in summer. This phenomenon is called a polar day. At the poles, the length of the day is six months.
The shortest and longest daylight hours occur during the winter and summer solstice. In the northern hemisphere, the winter solstice falls on December 21 or 22 (depending on the time zone), and the summer solstice falls on June 21 or 22 (in a leap year it can occur on June 20). Across the equator, in the Southern Hemisphere, the December solstice occurs in summer and the June solstice occurs in winter.
During the winter solstice, the length of daylight hours is only 5 hours 53 minutes. - this is the shortest day of the year and, accordingly, the longest night. The summer solstice makes it possible to live the longest day - 17 hours 33 minutes. Having reached its maximum duration, from this moment the daylight hours begin to decrease until the winter solstice comes again, and it starts to grow again.
For a long time, in the traditions of many peoples, the custom has been preserved to celebrate the days of the winter and summer solstices. So, in Russia, for example, a holiday called "Kolyada" is dedicated to the shortest day of the year.
Historians claim that the ancient Egyptians knew about the solstice. There is a version that they built the majestic pyramids in such a way that on the day of the summer solstice the sun would set between them. You can be convinced of this phenomenon by looking at the pyramids from the side of the Sphinx.
The famous British Stonehenge, located 130 km from London, is fraught with many mysteries and secrets. Some scientists call it the ancient observatory and also associate it with the summer solstice. Because it is on this day that the Sun rises above the Hillstone stone, located somewhat separate from the main structure.