Convert Synodic Months to Millennia
Convert Synodic Months (syn.mo) to Millennia (ka) instantly and accurately.
Conversion Formula
ka = syn.mo × 8.085200614e-5
About Synodic Months
A synodic (lunar) month = new moon to new moon = 29.5306 days = 2,551,442.9 s. Longer than the sidereal month (27.32 d) because Earth advances ~27° in its orbit during that time; the Moon must travel further to realign with the Sun. Islamic Hijri, Hebrew lunisolar, and Chinese calendars are built on synodic months. Eclipses repeat via the Saros cycle (18 yr 11 d = 223 synodic months). 1 syn.mo ≈ 29.5306 d.
About Millennia
A millennium (1 ka) = 1,000 Gregorian years ≈ 3.156 × 10¹⁰ s. Standard unit in archaeology and Quaternary geology: Neolithic transition ~10-12 ka BP; Last Glacial Maximum ~21 ka BP; Homo sapiens leaving Africa ~60-70 ka BP. Milankovitch cycles include the 41 ka obliquity and ~100 ka eccentricity cycle. EPICA Antarctic ice core spans ~800 ka. Precession completes ~26 ka. 1 ka = 1,000 yr.
Quick Reference Table
| Synodic Months (syn.mo) | Millennia (ka) |
|---|---|
| 1 syn.mo | 8.085 × 10-5 ka |
| 2 syn.mo | 0.000161704 ka |
| 5 syn.mo | 0.00040426 ka |
| 10 syn.mo | 0.00080852 ka |
| 25 syn.mo | 0.0020213 ka |
| 50 syn.mo | 0.0040426 ka |
| 100 syn.mo | 0.0080852 ka |