Moon 19th and 20th October 2018

With the clear and frosty nights we have seen some great moons the past week.

But how much of the Moon do we actually see?

Here's a method I thought of to work it out, using the idea that you really have two circles - the Moon's circumference and the circle formed by extrapolating the Terminator arc.

Working out the diameter of the Moon easy because the terminator 'horns' are always at the 'top' and 'bottom', and after a bit of fiddling, you can work out the distance between the left/right edge of the moon and the nearest part of the terminator.
(Don't forget the most you can ever see of the Moon is 50%!)

Time 17:45 / 20:00 (GMT).
Distance 249,599 / 247,779 miles.
Waxing gibbous / Waxing gibbous phase.
130 / 145 degrees SE / SE compass point (azimuth).
Altitude 8.1 / 20.8 degrees.