Convert Tropical Years to Megayears
Convert Tropical Years (a_trop) to Megayears (Ma) instantly and accurately.
Conversion Formula
Ma = a_trop × 9.999991512e-7
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 Megayears
A megayear (1 Ma) = 10⁶ yr ≈ 3.156 × 10¹³ s - the timescale of geology and tectonic evolution. The K-Pg mass extinction at 66.0 Ma; Cambrian explosion ~538.8 Ma; Great Oxygenation Event ~2,400 Ma. Plate motion at 2-10 cm/yr = 200-1,000 km per Ma (Atlantic ~3,000 km wider since Pangaea rifting ~200 Ma ago). Background extinction rate measured in extinctions per million species-years. 1 Ma = 10⁶ yr.
Quick Reference Table
| Tropical Years (a_trop) | Megayears (Ma) |
|---|---|
| 1 a_trop | 10 × 10-7 Ma |
| 2 a_trop | 2 × 10-6 Ma |
| 5 a_trop | 5 × 10-6 Ma |
| 10 a_trop | 10 × 10-6 Ma |
| 25 a_trop | 2.5 × 10-5 Ma |
| 50 a_trop | 5 × 10-5 Ma |
| 100 a_trop | 10 × 10-5 Ma |