"Why do we end each year on December 31st and begin a new one on January 1st anyway?" It wasn't always so. The months September, October, November, and December are the clue. They are Latin for seven, eight, nine and ten, but they are the ninth, tenth, eleventh and twelfth months. The original Roman calendar appears to have consisted only of 10 months and of a year of 304 days. The remaining 61 1/4 days were apparently ignored, resulting in a gap during the winter season. The months bore the names Martius, Aprilis, Maius, Juniius, Quintilis, Sextilis, September, October, November, and December. The Roman ruler
Numa Pompilius is credited with adding January at the beginning and February at the end of the calendar to create the 12-month year. In 452 BC, February was moved between January and March. January is named after the Roman god Janus, he had two faces so he could see the future and the past. He was also the god of doors. February's name is believed to stem from Februa, an ancient festival dedicated to ritual springtime cleaning and washing. The year, based on cycles and phases of the moon, totaled 365 and one quarter days, that is why we accumulate the quarter days and have a leap year with an extra day, every fourth year. Thirty days hath September, April, June and November. All the rest have thirty-one, Excepting February alone, And that has twenty-eight days clear And twenty-nine in each leap year. So now you know.