Convert Sidereal Years to Gregorian Years
Convert Sidereal Years (a_sid) to Gregorian Years (yr) instantly and accurately.
Conversion Formula
yr = a_sid × 1.000037956
About Sidereal Years
The sidereal year = Earth's orbital period relative to the stars = 365.25636 days = 31,558,149.8 s - about 20 min 24 s longer than the tropical year. The gap arises from precession of the equinoxes (~50 arcsec/year westward drift), which causes the tropical year to end slightly before the sidereal orbit completes. JPL DE440 ephemerides and J2000.0 epoch are anchored to the sidereal frame. 1 a_sid = 365.25636 d.
About Gregorian Years
The Gregorian year = exactly 365.2425 days = 31,556,952 s (mean over the 400-year cycle with 97 leap years). The Julian calendar (45 BCE) used 365.25 days; Gregorian reform (1582) dropped 10 days and amended the centennial rule. Britain adopted it in 1752; Greece in 1923. Carbon-14 dates are reported in 'years BP' (before 1950 CE). 1 yr = 365.2425 d = 8,765.82 h = 31,556,952 s.
Quick Reference Table
| Sidereal Years (a_sid) | Gregorian Years (yr) |
|---|---|
| 1 a_sid | 1.00004 yr |
| 2 a_sid | 2.00008 yr |
| 5 a_sid | 5.00019 yr |
| 10 a_sid | 10.0004 yr |
| 25 a_sid | 25.0009 yr |
| 50 a_sid | 50.0019 yr |
| 100 a_sid | 100.004 yr |