Convert Gigayears to Sidereal Days
Convert Gigayears (Ga) to Sidereal Days (sid.d) instantly and accurately.
Conversion Formula
sid.d = Ga × 366242501000
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.
About Sidereal Days
A sidereal day = Earth's rotation period relative to the stars = 23 h 56 min 4.0905 s = 86,164.0905 s - ~3 min 56 s shorter than the 24 h solar day because Earth advances ~1° in its orbit each day. Equatorial telescope mounts rotate at one turn per sidereal day to track stars. VLBI, GPS orbit determination, and polar-motion monitoring use sidereal rotation as their reference. 1 sid. day = 86,164.0905 s.
Quick Reference Table
| Gigayears (Ga) | Sidereal Days (sid.d) |
|---|---|
| 1 Ga | 3.662 × 1011 sid.d |
| 2 Ga | 7.325 × 1011 sid.d |
| 5 Ga | 1.831 × 1012 sid.d |
| 10 Ga | 3.662 × 1012 sid.d |
| 25 Ga | 9.156 × 1012 sid.d |
| 50 Ga | 1.831 × 1013 sid.d |
| 100 Ga | 3.662 × 1013 sid.d |