Early days
Question: The shortest day of the year in the northern hemisphere occurs on
21 or 22 December, yet the earliest sunset is on the 13 or 14 December and the
latest sunshine occurs a similar number of days after the shortest day. Why is
this?
Answer: Two properties of the Earth’s orbital motion around the Sun give rise
to the curious disparity between the dates of earliest sunset, shortest day
(winter solstice) and latest sunrise. These are the eccentricity of the Earth’s
orbit, and the tilt of its equator to its orbital plane.
The combined effect of these…
