Julian Years to Years (a to yr)
1 Julian year equals 1.000020534 years (rounded).
How to convert Julian years to years
To convert Julian years to years, multiply the number of Julian years by 1.000020534. The factor is rounded to 10 significant digits. To go the other way, multiply years by 0.9999794661 (rounded).
years = Julian years × 1.000020534
Example: 10 Julian years = 10.00020534 years.
Months and years are not constant. This site uses the average Gregorian year of 365.2425 days, so one 'year' converts to 365.2425 days, not 365; use 'common year' for exactly 365 days.
About these units
Julian Year (a)
Exactly 365.25 days (31,557,600 seconds). The astronomical standard; a light-year is defined using it.
Astronomers wanted a year that would never change, so they borrowed the average length of the old Julian calendar year: exactly 365.25 days of 86,400 SI seconds, or 31,557,600 seconds. The symbol is a, or aj when it must be told apart from other years. It is not an SI unit, but the IAU lists it among the non-SI units accepted for use in astronomy.
The mean tropical year drifts slightly from one year to the next, so it makes a poor unit, whereas the Julian year is constant because it rests on the SI second. It still approximates both the sidereal and tropical years to within about 0.008 days. The current standard epoch, J2000.0, is exactly 12:00 TT on 1 January 2000, and other Julian epochs are counted in Julian years from it. The light-year is defined as the distance light covers in one Julian year.
1 Julian year = 31,557,600 seconds (exactly).
Sources: Wikipedia: Julian year (astronomy); Wikipedia: Light-second; NIST SP 811 Appendix B.8: factors for units outside the SI
Year (yr)
The average Gregorian calendar year of 365.2425 days (31,556,952 seconds). A common year has 365 days and a leap year 366.
A year is the Earth's trip around the Sun, but there are several versions. The tropical year, which tracks the seasons, is about 365.2422 days. The sidereal year, measured against the stars, is about 365.2564 days, roughly 20 minutes longer, because the Earth's axis precesses. Calendars must squeeze these into whole days, which is the origin of leap years. English year descends from Old English gear, while Latin annus, the source of annual, comes from a different root.
The Gregorian calendar, introduced by Pope Gregory XIII's bull of 24 February 1582, fixed the problem of Julian drift that had moved the March equinox away from 21 March and upset the date of Easter. Ten days were skipped, so Thursday 4 October was followed by Friday 15 October. Its rule of skipping leap days in century years not divisible by 400 gives a mean year of 365.2425 days, the value this site uses for the year. Britain and its empire switched in 1752 and Russia in 1918. Scientists write the year as a, with the Julian year fixed at 31,557,600 seconds.
1 year = 31,556,952 seconds (exactly).
Sources: Wikipedia: Year; Wikipedia: Gregorian calendar
Related conversions
- Years to Julian years (reverse)
- Julian years to seconds
- Julian years to minutes
- Julian years to hours
- Julian years to days
- Julian years to weeks
- Julian years to months
- Seconds to years
- Minutes to years
- Hours to years
- Days to years
- Weeks to years
- Months to years
- Milliseconds to years
- Microseconds to years
- Nanoseconds to years
- Decades to years
- Centuries to years
- Millennia to years
See all time units.