Day Number

The day number is the number of days that has pasted since Jan. 1st of a given year.

Month Day Year   

Julian Date

The Julian Date is used to express an instant of observation as so many days after a given starting point.   Astronomers have chosen this as the Greenwich mean noon of January 1st 4713 B.C.  The number of days that have elapsed since that time is the Julian Day Number or Julian Date.  A new Julian Day starts at 12:00 UT, a half day out of step with the civil day in time zone 0.  The year 4713 B.C corresponds to -4712.

Month Day Year   

Julian Date to Calendar Date

Julian Date

The Day Of the Week

The Julian Date can be used to help find answers to other questions such as determining the day of the week.   Enter a date to see what day of the week that date falls on.

Month Day Year