In astronomy, a Julian year (symbol: a) is a unit to measure time. It has exactly 3651⁄4 days of 86,400 seconds each. That is the average length of the year in the Julian calendar used in Western societies in previous centuries, and for which the unit is named. Nevertheless, because a Julian year measures duration rather than designates date, the Julian year does not correspond to years in the Julian calendar or any other calendar. Nor does it correspond to the many other ways of defining a year (for which, see Year).
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- "Measuring the Universe". International Astronomical Union. Retrieved March 22, 2012.
- International Astronomical Union. "Recommendations Concerning Units". Archived from the original on February 16, 2007. Retrieved February 18, 2007. Cite uses deprecated parameter
|deadurl=(help) Reprinted from the "IAU Style Manual" by G.A. Wilkinson, Comm. 5, in IAU Transactions XXB (1987).
- Harold Rabinowitz and Suzanne Vogel, The manual of scientific style (Burlington, MA: Academic Press, 2009) 369.