4 ms·
A "real" day is 86164100 milliseconds (23h 56m 4.100s)
by m0skit0 8y ago
A "real" day is 86164100 milliseconds (23h 56m 4.100s)
- rimliu 8y agoAnd what makes stellar day real, and mean solar day not real? Having day defined in terms of the star Earth is orbiting around has a benefit of having more or less consistent time for noon. Having a day defined in terms of the mean sun instead of the real one has a benefit of having noons at exactly 24h apart instead of variable inter between noons of the real sun (see https://en.wikipedia.org/wiki/Equation_of_time https://en.wikipedia.org/wiki/Equation_of_time).
- jschwartzi 8y agoI never understood this until now. Thank you.
- jonsen 8y ago... what makes stellar day real, ... ? It's not really real, just side-real.
- m0skit0 8y ago"Real" is not real.
- cdelsolar 8y agoA solar day is still not exactly 86,400 seconds long.
- 205guy 8y agoI think there is a misunderstanding somewhere in here. m0skit0's comment was contrasting sidereal day (23h 56m 4.100s) to the original post concerning a mean solar day (24 hr 0m 0s). rimliu's comment seems to be saying that mean solar day has advantages over apparent solar day (each day has a different number of seconds that average to 24h 0m 0s over a year). I love the equation of time, but it is not related to sidereal time as discussed. Small correction to m0skit0: wikipedia says the sidereal day is 23h, 56m, 4.0905s to account for the 26,000 year procession of the March equinox.
- rimliu 8y agoI also mention measuring days with regard to the start we are orbiting (Sun and solar days) compared to the distant stars (sidereal days), so no misunderstanding here. Once again it is about having Sun at more or less its highest point in the sky at noon. With sidereal time it would constantly shift and if you had sun highest at noon today, if would be highest at midnight half year from now.