January 0

January 0 does not exist in any calendars. It sometimes refers to December 31.

In an ephimeris

January 0 also refers to the day before January 1 in an annual ephemeris. It keeps the date in the year for which the ephemeris was published. It avoids any reference to the previous year, even though it is the same day as December 31 of the previous year.

Software

In Microsoft Excel, the epoch of the 1900 date format is January 0, 1900.

Similar dates

• February 30, does not exist in Julian and Gregorian calendar, but it exists on Swedish calendar. February 30, 1951, is the last night of the world in Ray Bradbury's short story, "Last Night of the World".
• February 31, used on gravestones when the date is unknown.
• March 0, sometimes refer to February 28 or February 29.
• June 31, fictional date in the Soviet movie 31 June.