Convert Sidereal Years to Shakes
Convert Sidereal Years (a_sid) to Shakes (sh) instantly and accurately.
Conversion Formula
sh = a_sid × 3.155814976e+15
About Sidereal Years
The sidereal year = Earth's orbital period relative to the stars = 365.25636 days = 31,558,149.8 s - about 20 min 24 s longer than the tropical year. The gap arises from precession of the equinoxes (~50 arcsec/year westward drift), which causes the tropical year to end slightly before the sidereal orbit completes. JPL DE440 ephemerides and J2000.0 epoch are anchored to the sidereal frame. 1 a_sid = 365.25636 d.
About Shakes
A shake = exactly 10 ns (10⁻⁸ s) - the informal unit for fission prompt-neutron generation time, coined at Los Alamos during the Manhattan Project (1943-1945). A prompt-neutron generation in a supercritical core takes ~1-10 shakes; a full explosive chain reaction unfolds over ~50-100 shakes. The name alludes to 'two shakes of a lamb's tail'. Still used in reactor physics and weapons-design calculations. 1 shake = 10 ns.
Quick Reference Table
| Sidereal Years (a_sid) | Shakes (sh) |
|---|---|
| 1 a_sid | 3.156 × 1015 sh |
| 2 a_sid | 6.312 × 1015 sh |
| 5 a_sid | 1.578 × 1016 sh |
| 10 a_sid | 3.156 × 1016 sh |
| 25 a_sid | 7.89 × 1016 sh |
| 50 a_sid | 1.578 × 1017 sh |
| 100 a_sid | 3.156 × 1017 sh |