Convert Julian Years to Megayears
Convert Julian Years (a_J) to Megayears (Ma) instantly and accurately.
Conversion Formula
Ma = a_J × 1.000020534e-6
About Julian Years
The Julian year (a_J) = exactly 365.25 days = 31,557,600 s - the IAU standard year for astronomical distances. The light-year is formally 1 ly = c × 1 a_J = 9.461 × 10¹⁵ m (IAU 2012 B2). Julian years differ from Gregorian years by only 648 s (~10.8 min/year); important for high-precision astrometry or calculations spanning centuries. 1 a_J = 365.25 d = 31,557,600 s.
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
| Julian Years (a_J) | Megayears (Ma) |
|---|---|
| 1 a_J | 1 × 10-6 Ma |
| 2 a_J | 2 × 10-6 Ma |
| 5 a_J | 5 × 10-6 Ma |
| 10 a_J | 1 × 10-5 Ma |
| 25 a_J | 2.5 × 10-5 Ma |
| 50 a_J | 5 × 10-5 Ma |
| 100 a_J | 0.000100002 Ma |