It's the first day of the New Year! Or not. Maybe the New Year doesn’t start until March 15th. Or, sometime next October. Who knows? January 1st is, after all, an arbitrary date picked by a Pope in the 16th Century while the Spanish Armada was headed to England.
For over 1600 years the standard calendar for most of the world was the Julian Calendar, designed by Julius Caesar in 45 B.C. A great accomplishment but based on round numbers. The earth and the sun, however, do not operate in round numbers and the calendar was doomed to fall apart. By the 16th century it was obvious by simply observing the spring equinox that the calendar was off. Way off.
In 1582 Pope Gregory XIII launched the calendar we use today. He had to cheat to make the numbers work – he deleted October 5 - October 14th, 1482. He undated them. They never happened. Then he finagled the ‘leap-year-every-four-years-except on centennial years that aren’t divisible by 400.’
‘Centennial years not divisible by 400’ – you have to wonder how much trial and error went into that not-so-scientific calculation.
Gregory finished by changing New Year's Day from March 15th to January 1st.