Convert Sidereal Months to Days
Convert Sidereal Months (sid.mo) to Days (d) instantly and accurately.
Conversion Formula
d = sid.mo × 27.32166169
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 Days
A day (d) = exactly 86,400 s. Earth's actual solar day varies ±16 s due to orbital eccentricity and axial tilt (equation of time). Leap seconds (abandoned in UTC after 2035) corrected the TAI-UT1 divergence. Mars's sol = 24 h 39 min 35 s ≈ 88,775 s; a Martian year = 668.6 sols. The day structures circadian biology, tides, and planetary science. 1 day = 86,400 s = 24 h.
Quick Reference Table
| Sidereal Months (sid.mo) | Days (d) |
|---|---|
| 1 sid.mo | 27.3217 d |
| 2 sid.mo | 54.6433 d |
| 5 sid.mo | 136.608 d |
| 10 sid.mo | 273.217 d |
| 25 sid.mo | 683.042 d |
| 50 sid.mo | 1366.08 d |
| 100 sid.mo | 2732.17 d |