A sidereal day is approximately how much shorter than a solar day?
Official USCG Answer & Rule Citation
Correct Answer: Option A — 4 minutes
A sidereal day is shorter than a solar day by approximately 3 minutes and 56 seconds, commonly rounded to 4 minutes. As detailed in Bowditch, this discrepancy arises because Earth must rotate slightly more than 360 degrees to bring the Sun back to the same meridian daily.
100% Free & Open Access — No daily limits, paywalls, or gated answers on BrightMariner.