Christmas Day is celebrated on December 25. Many people look on Christmas as the time to celebrate the birth of Jesus Christ, but really the tradition goes back to the earliest of times.In those days the sun meant so much to primitive man that when it began to go lower each day till December 23, people thought the sun was going to die out and they were worried. ... On December 23 the sun stayed in the sky longer and longer and after that the nights were becoming shorter and shorter. ...