| Share
 

Julian Day calendar

Julian Day calendar, system of astronomical dating that allows the difference between two dates to be calculated more easily than conventional civil calendars with their uneven months. It was devised by Joseph Scaliger in 1582 and named in honor of his father, Julius Caesar Scaliger. The Julian period of 7,980 years is a product of the solar cycle, the lunar cycle, and the Roman indiction cycle and begins on Jan. 1, 4713 B.C., that being the nearest past year in which the three cycles coincided. Dates are numbered consecutively from that day, regardless of the various changes made in civil calendars based on changing definitions of the year. The Julian Day number for Dec. 31, 1999, is 2,451,544; for Jan. 1, 2000, is 2,451,545; for Jan. 2, 2000, is 2,451,546; and so on. The Julian Day is from noon, universal time, on the given date to noon of the following date.

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

More on Julian Day calendar from Infoplease:

See more Encyclopedia articles on: Astronomy: General


Premium Partner Content
HighBeam Research
Documents Images and Maps Reference
(from Newspapers, Magazines, Journals, Newswires, Transcripts and Books)

Research our extensive archive of more than 80 million articles from 6,500 publications.

Additional search results provided by HighBeam Research, LLC. © Copyright 2005. All rights reserved.

24 X 7

Private Tutor

Click Here for Details
24 x 7 Tutor Availability
Unlimited Online Tutoring
1-on-1 Tutoring