On Friday, May 12, 2017 at 5:32:12 PM UTC+1, Chris.B wrote:
On Friday, 12 May 2017 13:59:35 UTC+2, wrote:

The circle of illumination does not expand or contract.

Apparently you are still some way from your Primary School Geography qualification.

You cannot shame a psychopathic bully into accepting their own failures. Their own glaring, behavioural handicaps are always their critic's fault. Ask any racist, wife beater, troll, criminal, bad driver, extremist or terrorist for instant confirmation with the first breath. Infantile paralysis of their conscience denies them any empathy with their countless, bloodied victims. "They made me do it, Mommy!"

http://www.bbc.com/news/world-europe-39895427

You are in love with your own words and make a racket on that account.

Not being clear in my last contribution , the circumference where the Sun remains in view constantly expands presently with the North pole at its center while the opposite is the case at the South pole where the circle of planetary surface where the Sun is absents expands in similar fashion. As the North poles turns across the fully illuminated face of the Earth and parallel to the orbital plane so that the distance between that surface point and the circle of illumination grows and providing the basis for expansion/contraction of areas exposed to constant sunlight or constant darkness.

The object of this exercise is not only to provide an accurate description of conditions at either poles but also to prevent people from reaching for the old incomplete and ultimately false description of the Northern and Southern poles tilting towards and away from the Sun.