🌀 What if Earth rotated twice as fast?
A 12-hour day, stronger equatorial bulge, and launch sites would love it.
Try it: Earth Rotation Laboratory
- Day length (sidereal)
- 23.934 hours
- Equatorial surface speed
- 1,672.52 km/h
- Centrifugal acceleration (equator)
- 0.0338791 m/s²
- Effective gravity (equator)
- 9.77277 m/s²
Simplified: spherical Earth, equator only. Does not model shape change, oceans, atmosphere or geology.
Equations: T = T₀/f · v = f·ω₀·R · a = (f·ω₀)²·R · g_eff = g − a. Reference: sidereal day 23.934 h, Earth radius 6,371 km.
The science
Doubling rotation halves the sidereal day to about 12 hours. Equatorial surface speed doubles to ~3,340 km/h, and centrifugal acceleration — which grows with the square of speed — quadruples. Use the Earth Rotation Laboratory below with the slider set to 2× to see the numbers.
Immediate consequences (modelled)
Days halve; equatorial effective gravity falls slightly; satellites in low orbit are unaffected but geostationary orbit moves closer.
Possible long-term consequences (hypotheses)
Over geological time Earth would bulge more at the equator and flatten at the poles; weather bands and ocean currents would reorganise. These are hypotheses, not certainties.
Assumptions: Equations: T = T₀/f, v = f·ω₀·R, a = (f·ω₀)²·R, g_eff = g − a (equator, spherical Earth).
Limitations: Does not model climate, geology, biology or engineering in full detail.
Reference: NASA / peer-reviewed planetary science