Convert Sidereal Years to Gigayears
Convert Sidereal Years (a_sid) to Gigayears (Ga) instantly and accurately.
Conversion Formula
Ga = a_sid × 1.000037956e-9
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 Gigayears
A gigayear (1 Ga) = 10⁹ yr ≈ 3.156 × 10¹⁶ s - the timescale of stellar evolution and cosmology. Universe age: 13.787 ± 0.020 Ga (Planck CMB). Sun: 4.603 Ga old; red giant in ~5 Ga. A 0.1 M☉ red dwarf lives ~10,000 Ga. Uranium-238 half-life = 4.468 Ga (used in radiometric dating). Proton decay (GUT prediction): ~10³⁴ yr = ~10²⁵ Ga. 1 Ga = 10⁹ yr.
Quick Reference Table
| Sidereal Years (a_sid) | Gigayears (Ga) |
|---|---|
| 1 a_sid | 1 × 10-9 Ga |
| 2 a_sid | 2 × 10-9 Ga |
| 5 a_sid | 5 × 10-9 Ga |
| 10 a_sid | 1 × 10-8 Ga |
| 25 a_sid | 2.5 × 10-8 Ga |
| 50 a_sid | 5 × 10-8 Ga |
| 100 a_sid | 1 × 10-7 Ga |