Convert Tropical Years to Anomalistic Months
Convert Tropical Years (a_trop) to Anomalistic Months (anom.mo) instantly and accurately.
Conversion Formula
anom.mo = a_trop × 13.2552401
About Tropical Years
The tropical year = time from March equinox to the next = 365.24219 days = 31,556,925.2 s - the year that governs the seasons. The Gregorian 97/400 leap rule approximates it as 365.2425 days, leaving a residual drift of only ~26.8 s/year. The tropical year shortens ~0.53 s per century due to tidal deceleration. Persian Solar Hijri and Mayan Haab' calendars also approximate it. 1 a_trop ≈ 365.24219 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
| Tropical Years (a_trop) | Anomalistic Months (anom.mo) |
|---|---|
| 1 a_trop | 13.2552 anom.mo |
| 2 a_trop | 26.5105 anom.mo |
| 5 a_trop | 66.2762 anom.mo |
| 10 a_trop | 132.552 anom.mo |
| 25 a_trop | 331.381 anom.mo |
| 50 a_trop | 662.762 anom.mo |
| 100 a_trop | 1325.52 anom.mo |