3 ms·
> how close to a sine wave is the Daylight line? It's as close as the Earth's orbit is to a perfect circle and that the shapes of the earth and sun are to perf
by SideQuark 2y ago
> how close to a sine wave is the Daylight line?
It's as close as the Earth's orbit is to a perfect circle and that the shapes of the earth and sun are to perfect spheres and as the axis of the earth has no wobble and no precession and the sun's rays are truly parallel and and there is no drag in space sapping energy from the dynamics and general relativity effects are sent to zero and so on.
Once everything is perfectly circular and simple and Euclidean, then it does become a perfect sinewave. Then the sinewave has period = 1 year, the amplitude is symmetric by latitude, and it's pretty easy to derive.
All the above (and more) all intorduce measurable errors from the perfect sinewave.
- rachofsunshine 2y agoOr for those who prefer their deviations from ideal behavior in pretty curve form, the analemma [1] captures the way in which the Sun's fails to return to the same point in the sky each day: - The north-south component comes from the Earth's axial tilt - The asymmetry from north to south comes from the elliptical nature of Earth's orbit, which is closer/faster in northern winter + further/slower in northern summer. - The east-west movement comes from the equation of time, which is mostly a mix of the Earth's axial tilt and the eccentricity of its orbit. [1] https://en.wikipedia.org/wiki/Analemma https://en.wikipedia.org/wiki/Analemma