Convert Sidereal Months to Draconic Months
Convert Sidereal Months (sid.mo) to Draconic Months (drac.mo) instantly and accurately.
Conversion Formula
drac.mo = sid.mo × 1.004021785
About Sidereal Months
The sidereal month = Moon's orbital period relative to the fixed stars = 27.3217 days = 2,360,591.6 s - the shortest lunar month. It is ~2.21 days shorter than the synodic month (29.53 d) because Earth advances ~27° along its orbit in the same period; the Moon must travel further to re-align with the Sun. Used in GPS orbit design, tidal modelling, and lunar laser ranging. 1 sid.mo = 27.3217 d.
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.
Quick Reference Table
| Sidereal Months (sid.mo) | Draconic Months (drac.mo) |
|---|---|
| 1 sid.mo | 1.00402 drac.mo |
| 2 sid.mo | 2.00804 drac.mo |
| 5 sid.mo | 5.02011 drac.mo |
| 10 sid.mo | 10.0402 drac.mo |
| 25 sid.mo | 25.1005 drac.mo |
| 50 sid.mo | 50.2011 drac.mo |
| 100 sid.mo | 100.402 drac.mo |