JulianDate
gives the current number of days since noon on November 24, 4714 BCE in the GMT time zone.
JulianDate[date]
gives the number of days for the specified date.
JulianDate["type"]
gives the Julian date variant of the specified type.
JulianDate["type",date]
gives the variant for the specified date.
Details

- In JulianDate[date], date can be a DateObject, a date string, a {y,m,d,h,m,s} date list, or a number corresponding to an absolute time specification.
- JulianDate[date] assumes that the given date is in $TimeZone, unless it is a DateObject or TimeObject with an explicit TimeZone option value.
- The result of JulianDate is a number of days, including a fractional part giving the time since the previous noon in GMT.
- Shorter lists can be used in JulianDate[{y,m,…}]: {y} is equivalent to {y,1,1,0,0,0}, {y,m} to {y,m,1,0,0,0}, etc.
- Values of m, d, h, m, s outside their normal ranges are appropriately reduced. Noninteger values of d, h, m, s can also be used.
- Possible Julian date variants include:
-
"Reduced" relative to noon on November 16, 1858 "Modified" relative to midnight on November 17, 1858 (MJD) "Truncated" relative to midnight on May 24, 1968 (TJD) "Dublin" relative to noon on December 31, 1899 (DJD) "Full" relative to noon on November 24, 4714 BCE (JD) - The default Julian date variant used is "Full". All referenced dates are using the proleptic Gregorian calendar.
Examples
open allclose allBasic Examples (3)
Scope (6)
Inputs are assumed to be in $TimeZone. Block can be used to specify a different input timezone:
Use DateObject to specify an input in a different TimeZone:
Separators are assumed if not specified:
Date lists are converted to standard normalized form:
Day, hour, minute, and second values in input date lists can be noninteger:
Properties & Relations (3)
JulianDate[date] converts date into Julian date format:
FromJulianDate converts from Julian date format into a DateObject expression:
Julian date 0 corresponds to this date in the proleptic Gregorian calendar for the GMT time zone:
It corresponds to noon January 1, in the Julian calendar for the GMT time zone:
Convert back to Julian date 0:
JulianDate is an affine transform of AbsoluteTime: rescale from seconds to days and add a constant:
Text
Wolfram Research (2015), JulianDate, Wolfram Language function, https://reference.wolfram.com/language/ref/JulianDate.html.
BibTeX
BibLaTeX
CMS
Wolfram Language. 2015. "JulianDate." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/JulianDate.html.
APA
Wolfram Language. (2015). JulianDate. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/JulianDate.html