Convert Draconic Months to Sidereal Years
Convert Draconic Months (drac.mo) to Sidereal Years (a_sid) instantly and accurately.
Conversion Formula
a_sid = drac.mo × 0.07450170006
About Draconic Months
The draconic (nodical) month = 27.2122 days = 2,351,135.8 s - the interval between successive Moon passages through the same orbital node. Named from the Latin 'draco' (dragon): eclipses only occur near the nodes, where the Moon can align with the Sun or Earth's shadow. The Saros cycle (18 yr 11 d) equals ~242 draconic months, enabling eclipse sequence forecasting. 1 drac.mo = 27.2122 d.
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.
Quick Reference Table
| Draconic Months (drac.mo) | Sidereal Years (a_sid) |
|---|---|
| 1 drac.mo | 0.0745017 a_sid |
| 2 drac.mo | 0.149003 a_sid |
| 5 drac.mo | 0.372509 a_sid |
| 10 drac.mo | 0.745017 a_sid |
| 25 drac.mo | 1.86254 a_sid |
| 50 drac.mo | 3.72509 a_sid |
| 100 drac.mo | 7.45017 a_sid |