Solstice December 2018

Today marks the great astronomical event of two distinct noon events and two midnight events, one daily and the other polar within the same 24 hour day.

https://www.usap.gov/videoclipsandmaps/spwebcam.cfm

The distance between that location and the circle of illumination is now at a maximum giving rise to the Antarctic circle where the Sun is now constantly in view across the largest area with the South Pole at the centre -

https://www.youtube.com/watch?v=-OgLCH7jYp8

The orbital plane cuts through the maximum diameter of the Earth and represented by the broken line in the following graphic -

http://afewbitsmore.com/img/2015_ecliptic.png

The orbital surface rotation at the maximum circumference is, on average, about 68. 2 miles per 24 hour day. At the North and South Polar latitudes, that speed reduces to 30 miles per day consistent with the original perspective of Copernicus -

"The third is the motion in declination. For, the axis of the daily rotation is not parallel to the Grand Orb's axis, but is inclined [to it at an angle that intercepts] a portion of a circumference, in our time about 23 1/2°. Therefore, while the earth's center always remains in the plane of the ecliptic, that is, in the circumference of a circle of the Grand Orb, the earth's poles rotate, both of them describing small circles about centers [lying on a line that moves] parallel to the Grand Orb's axis. The period of this motion also is a year, but not quite, being nearly equal to the Grand Orb's [revolution]." Copernicus