Julian Date : Java Glossary

2007-10-10 by Roedy Green ©1996-2009 Canadian Mind Products
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Julian Date

I have seen term Julian day/date used for :

Proleptic day numbers (astronomy). Use BigDate.getProlepticJulianDay() to calculate them. Day 0 began Julian 4713 BC Jan 1 noon GMT (Gregorian 4714 BC Nov 24) It has no months or leap years, just day numbers.
Modified Julian Date is proleptic minus 2400000.5. It ticks over at midnight UTC instead of noon, and the numbers are smaller for recent events. The MJD has been officially recognized by the International Astronomical Union (IAU), and by the Consultative Committee for Radio (CCIR), the advisory committee to the International Telecommunications Union (ITU).
CJD Chronological Julian Date and CMJD Chronological Modified Julian Date which are relative to local civil time.
Catholic calendar prior to Pope Gregory’s 100 and 400 year leap year corrections. It was also used by protestants.
YYDDD or YYYYDDD, using the Gregorian calendar.
DDD-YYYY, using the Gregorian calendar.
Days since some epoch, e.g. 4713 BC Jan 01, 0001 Jan 1, 1860-01-01, 1900-01-01, 1970-01-01, using the Gregorian calendar. In the BigDate class I call these day counts date ordinals.
Any sort of date/timestamp, usually milliseconds since 1970-01-01 00:00:00 UTC.
Even YYMMDD or YYYYMMDD with the Gregorian calendar. This makes so sense.

Don’t trust Julian to mean much more than "something other than the conventional locale date format." A day is an earthly revolution. Because of man’s activities moving water around the planet, it has actually changed the length of the day measurably.

BigDate
Calendar
Calendar FAQ
GregorianCalendar
leap second
leap year
missing days
Which Julius?

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