DateInfo
See Also: Daylight - Application to show which parts of the Earth are in daylight.
Instructions
This program calculates and displays calendar-related information. For a given date, the following information is
available:
- The date in the Gregorian calendar. This is the currently used calendar by most of the world,
and was first decreed by Pope Gregory XIII in February 1582.
- The Julian Day Number. This number is sometimes used in astronomy, and uniquely indentifies
every day since 1 January 4713 BC.
- The date of the next new moon. An estimate, usually to within one day.
- The date in the Julian Calendar. This older calendar was introduced by Julius Caesar in 45 BC.
It remained in use in Britain (and dominions) until September 1752. It was then replaced by the Gregorian calendar
due to the latter's superior leap year system.
- The date in the Mayan Calendar. The ancient Maya developed a calendar which used three
different dating systems in parallel. These are (1) the "Long Count" - a system of five digits "A.B.C.D.E" which
counted days since the start of the Mayan era; (2) the "Tzolkin" (divine calendar) which described each day by a
named part and a digit which cycle every 260 days; (3) the "Haab" (civil calendar) which has a month/day
arrangement which cycles every 365 days. In this respect the Haab is similar to the modern Western calendar.
- The approximate date in the Islamic Calendar. This cannot be calculated precisely as it
depends on lunar observation - the program estimates the date with a typical error of one or two days.
- The Chinese year. The start date of the Chinese year cannot be reliably predicted, but is
generally in January or February. For convenience, this program assumes it is 1st January.
- For any given year, the Golden Number and the Epact. These are numbers related to the cycles
of the Sun and the Moon. They are used to calculate the date of Easter, and were also used in olden times to
predict solar eclipses.
- The dates of the Paschal full moon and Easter Sunday. The Paschal full moon is the first full
moon after the vernal equinox (21 March). Easter Sunday is defined as the next Sunday after that.
- The number of days between two dates. If a reference date is supplied, the program will
calculate the number of days between the reference and the current date. You can use this to find out how many days
old you are!
All textfields can be modified - type new values and press ENTER. All dates are written in International
Standard IS-8601 "year-month-day" format. No guarantees are made regarding accuracy or correctness of this software.
See Also: Daylight Applet.
I would like to acknowledge Claus Tondering's Calendar FAQ for a wealth of information.
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