Julian epoch


Julian epoch
(J)
   a measure of time used in astronomy. The word epoch comes from Greek, and means a fixed or standard instant of time. Other times are stated with reference to this fixed time using years and fractions of years. In 1984, astronomers agreed to fix the standard epoch at 12 hours Universal Time of 2000 January 1 (JD 2 451 545.0). This instant is designated J2000.0. Other times are specified with reference to this time using a year of length 365.25 days, the average length of the year in the Julian calendar. This means that J2001.0, for example, is 18 hours Universal Time of 2001 January 1 (exactly 365.25 days after J2000.0). See Julian year, below.

Dictionary of units of measurement. 2015.

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  • Julian epoch — Julian Jul ian (?; 277) a. [L. Julianus, fr. Julius. Cf. {July}, {Gillian}.] Relating to, or derived from, Julius C[ae]sar. [1913 Webster] {Julian calendar}, the calendar as adjusted by Julius C[ae]sar, in which the year was made to consist of… …   The Collaborative International Dictionary of English

  • Julian — Jul ian (?; 277) a. [L. Julianus, fr. Julius. Cf. {July}, {Gillian}.] Relating to, or derived from, Julius C[ae]sar. [1913 Webster] {Julian calendar}, the calendar as adjusted by Julius C[ae]sar, in which the year was made to consist of 365 days …   The Collaborative International Dictionary of English

  • Julian calendar — Julian Jul ian (?; 277) a. [L. Julianus, fr. Julius. Cf. {July}, {Gillian}.] Relating to, or derived from, Julius C[ae]sar. [1913 Webster] {Julian calendar}, the calendar as adjusted by Julius C[ae]sar, in which the year was made to consist of… …   The Collaborative International Dictionary of English

  • Julian period — Julian Jul ian (?; 277) a. [L. Julianus, fr. Julius. Cf. {July}, {Gillian}.] Relating to, or derived from, Julius C[ae]sar. [1913 Webster] {Julian calendar}, the calendar as adjusted by Julius C[ae]sar, in which the year was made to consist of… …   The Collaborative International Dictionary of English

  • Julian year — Julian Jul ian (?; 277) a. [L. Julianus, fr. Julius. Cf. {July}, {Gillian}.] Relating to, or derived from, Julius C[ae]sar. [1913 Webster] {Julian calendar}, the calendar as adjusted by Julius C[ae]sar, in which the year was made to consist of… …   The Collaborative International Dictionary of English

  • Julian year (astronomy) — In astronomy, a Julian year (symbol: a) is a unit of measurement of time defined as exactly 365.25 days of 86,400 SI seconds each, totalling 31,557,600 seconds. That is the average length of the year in the Julian calendar used in Western… …   Wikipedia

  • epoch —    1. a measure of time used in astronomy. In an epoch system, times are specified as years and fractions of years (such as epoch 1998.5). To set a starting point for the system, a specific epoch time must be fixed as a particular clock time of a …   Dictionary of units of measurement

  • Julian Klaczko —     Julian Klaczko     † Catholic Encyclopedia ► Julian Klaczko     Polish author, b. at Vilna, 6 November, 1825, of Jewish parents; d. at Cracow, 26 November, 1906. After taking the doctor s degree in 1847 at the University of Königsberg, he… …   Catholic encyclopedia

  • Julian Stryjkowski — (born Pesach Stark , 1905 1996) was a Polish journalist and writer, notable for his social prose of leftists character.He was born April 27, 1905 in Stryj (modern Ukraine), to a family of Hasidic Jews. He graduated from the Faculty of Polish… …   Wikipedia

  • Julian day — JDN redirects here. For the military IT system, see Joint Data Network. For the comic book character Julian Gregory Day, see Calendar Man. Not to be confused with Julian year (disambiguation). Julian day is used in the Julian date (JD) system of… …   Wikipedia


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