On Friday, March 15, 2019 at 1:07:36 PM UTC-6, Gerald Kelleher wrote:

In a number of days, the Sun will disappear from view for 6 months

Of course, this applies to the immediate vicinity of the South Pole, as your link
makes apparent.

in what is one of the great astronomical events - two distinct types of sunrise
and sunset within the same 24 hour day.

And these two distinct types of sunrise and sunset are consequences of the Earth
having two distinct rotational motions. One being "orbital rotation", the other
being "daily rotation" as I think you call them.

Now, then, as I am sure you are aware, the Earth is a rigid body. This means
that these two types of rotation are inseparable, and every part of the Earth
experiences both of them.

This means that since "orbital rotation" has a period of one year, in order for
people at temperate and tropical latitudes to experience a 24 hour day, "daily
rotation" must have a period differing from 24 hours, in order that the _sum_ of
daily rotation and orbital rotation will yield a 24 hour day.

So "daily rotation" must have a period of 23 hours, 56 minutes, and 4 seconds,
or thereabouts.

John Savard