It is believed that the 24-hour day concept came from ancient Egyptians, who divided the time between sunrise and sunset into ten hours, and kept one hour for each twilight period and 12 hours for nighttime. The Babylonians and Greeks then divided each hour into 60 minutes, and each minute into 60 seconds, which became the basis of modern timekeeping.
The shortest day of the year lasts for 7 hours 49 minutes and 41 seconds in Britain. This day is 8 hours, 49 minutes shorter than the June Solstice. The winter solstice happens every year when the Sun reaches its most southerly declination of -23.5 degrees. In other words, when the North Pole is tilted farthest – 23.5 degrees – away from the Sun, delivering the fewest hours of sunlight of the year.In the Southern Hemisphere, the opposite is true. Dawn comes early, and dusk comes late. The sun is high and the shortest noontime shadow of the year happens there. In the Southern Hemisphere, people will experience their longest day and shortest night.