Sidereal Years to Years (yr (sid) to yr)
1 sidereal year equals 1.000037956 years (rounded).
How to convert sidereal years to years
To convert sidereal years to years, multiply the number of sidereal years by 1.000037956. The factor is rounded to 10 significant digits. To go the other way, multiply years by 0.9999620458 (rounded).
years = sidereal years × 1.000037956
Example: 10 sidereal years = 10.00037956 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.
Approximate value. Standards for the sidereal year varied by place and period, so this converter uses the most commonly cited value. Treat results as estimates, not exact figures.
About these units
Sidereal Year (yr (sid))
About 365.256363 days, the time for Earth to return to the same position relative to the fixed stars.
Measured against the fixed stars, one orbit of Earth around the Sun takes about 365.256363 days, or roughly 365 days 6 hours 9 minutes 10 seconds. That is the sidereal year, and it is about 20 minutes 25 seconds longer than the mean tropical year used for the seasons.
The gap exists because of the precession of the equinoxes, which Hipparchus identified in 127 BC after comparing the two kinds of year. Ptolemy later reported his sidereal figure as about 365 days 6 hours 10 minutes, already close to the modern value. Earlier peoples had tracked the year by star events instead, such as the Egyptian watch for the rising of Sirius before the Nile flood, and Hesiod's farming advice tied to the Pleiades.
Indian astronomy kept the sidereal year in its calendars. The Surya Siddhanta gave a value near 365 days 6 hours 12 minutes 36.56 seconds, slightly long by modern measurement. NASA's fact sheet lists the sidereal orbital period of Earth as 365.256 days.
1 sidereal year = 31,558,149.76 seconds (approximately).
Sources: Wikipedia: Sidereal year; NASA Earth Fact Sheet
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 sidereal years (reverse)
- Sidereal years to seconds
- Sidereal years to minutes
- Sidereal years to hours
- Sidereal years to days
- Sidereal years to weeks
- Sidereal 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.