Winter holidays in many cultures originated as ancient people observed the changes in the sun’s height in the sky and the corresponding length of the day. Every day for the past six months the Sun has been lower in the sky and there have been fewer hours of daylight. This past Wednesday, December 21st, the Winter Solstice, was the shortest day of the year with the shortest time span between sunrise and sunset. Here in San Francisco, CA, there were 9 hours and 33 minutes of sunlight. At 1:47 pm PST, the Sun was directly above the Tropic of Capricorn, 23.5 degrees south of the equator. Now for the next six months the tilt of the Earth in relation to our orbit around the Sun will make each day longer until the Summer Solstice.