Convert Sidereal Months to Anomalistic Months
Convert Sidereal Months (sid.mo) to Anomalistic Months (anom.mo) instantly and accurately.
Conversion Formula
anom.mo = sid.mo × 0.9915480622
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 Anomalistic Months
The anomalistic month = interval between successive Moon perigees = 27.5546 days = 2,380,713.2 s. Slightly longer than the sidereal month because the Moon's perigee precesses, completing one revolution in ~8.85 years. Governs 'supermoons': a full moon at perigee appears ~14% wider and 30% brighter. Tidal forces at perigee are ~30% stronger than at apogee. 1 anom.mo = 27.5546 d.
Quick Reference Table
| Sidereal Months (sid.mo) | Anomalistic Months (anom.mo) |
|---|---|
| 1 sid.mo | 0.991548 anom.mo |
| 2 sid.mo | 1.9831 anom.mo |
| 5 sid.mo | 4.95774 anom.mo |
| 10 sid.mo | 9.91548 anom.mo |
| 25 sid.mo | 24.7887 anom.mo |
| 50 sid.mo | 49.5774 anom.mo |
| 100 sid.mo | 99.1548 anom.mo |