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Perpetual Calendar
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The Countdown To
Christmas 2008
Days : Hours : Minutes : Seconds
Counting Down From
Your Current Local Time
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International Internet Time
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Julian Day and Date Time Calculator
These converters require the use of Javascript enabled and capable browsers. The calendar in the top left screen quadrant is a perpetual monthly display with the current date always displayed in it's own lower right quadrant. The double arrows allow movement in time backward (-) or forward (+) a month or year per click. The upper right quadrant is an emulated digital display of a countdown to Christmas morning, December 25, 2003, the (YOUR) local time, and the International Internet Time in SwatchBeats. Below that, the lunar data is derived and displayed for informational purposes only; it cannot be used in the calculations. Calculated accuracy of most current Javascript enabled browsers is generally 16 places. All entry fields are individually editable; all fields are verified for validity. Change the date to calculate the Julian Day Number (JD#) and day of the week, or vice versa. Be certain to a enter positive year (there are no negative years), then specify A.D. or B.C.; remember, there was no year 0 (zero) so 0 is not a valid year.
After changing a text box, click outside of the calculator, or press tab on the keyboard, to calculate and display all other data. In the AutoSelect mode (the default mode), the civil calendar changes from Julian to Gregorian between October 4/15, 1582. For Julian civil dates after that date, as in England and colonies until 1753, select Use Julian Only. A Julian date is valid from January 1, 4713 B.C. to present. For Financial dates and legal dates, days between dates, days before a date or days after a date, day of the week for a given date in history, involving the last 2 centuries, use the AutoSelect mode. Be sure to see the information below the calculator for general information about the Julian and Gregorian (accepted as our current civil calendar) calendars. In this calculator, we have avoided the "time of day" factor. It is briefly discussed below. If you have the need for that, you can use our calendar date to Julian date and time calculator or our calendar date and time From Julian date calculator.
Lunar Information
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Modify the following field ONLY to determine the date "this number of days" before or after another date calculation result (or just a date) in the Input Data For Calculation field. Use a negative number for days preceding and a positive number for days following. Otherwise, if left at 0 (zero), this number will be calculated to yield the number of days between dates manually set in each of the date fields. This field can be a factor or a result, depending on the way YOU decide to use it and the two associated date fields.
As an example, the dates by default, are both TODAY's date and the days between is obviously zero (0). However, if you wish to know the date 46 days after today, put 46 in the Optional Input Data For Calculation, also called the "math" field, click anywhere on the page (or press tab) and see the result in the result date area below it. If you wanted to know what day was 46 days PRIOR to today, put a -46 in the math field. The area designated as Input Data For Calculation, also called the "subject" date, is always the first one and the Calculated Results area, also called the "result" date, is always the second one. How can you use it? Another example might be as follows. It takes your company 30 days to get a check for payables through a process for mailing. The payment is due on a certain date. Put that date in the "subject" date area. Then put in -30 in the math field and read the day the process must "start by" in the "result" area. There are many possibilities. If you are wanting to know the number of days between two different dates, we suggest that you use our simplified Days Between Dates Calculator.
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Optional Input Data For Calculation
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Version 8.3.3
In astronomy, a JD (Julian Date) is defined as the contiguous count of days from January 1, 4713 B.C., Greenwich Mean Noon (equal to zero hours UTC). The fraction of each day is represented as a decimal number. Hence noon (GMT) on January 2, 4713 B.C. would have JD# (Julian Date number) 1.00000, 6.00 pm GMT on the same day would have JD# 1.25000 and 6.00 hours Coordinated Universal Time (UCT) would have JD# 2443509.75.
Why was January 1, 4713 B.C. chosen as the starting point? According to most knowledgeable sources on the subject, it is the most recent day (certainly that I can remember...) in which the year began on a Sunday with a full moon. Also day 1 was chosen as January 1, 4713 B.C. because the Julian Calendar, the Lunar Calendar and the Roman Tax Calendar all coincided. This happens every 7,980 years, so the next coincidence will be in 3267 A.D. I'll let you know if it actually happens that way next time...
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Calendar Date to Julian Date and Time Calculator
Calendar Date and Time From Julian Date Calculator
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