NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tibor Miseta
Date: 2024 Feb 18, 02:32 -0800
Thanx for the puzzle, a found it very intresting!
Although it looks like Africa at the very first look, it could not be! There is a very special shaped bay along the coastline (lower side, Spencer Gulf) that could not be found in Africa. So my guess was Australia based on the shape of the landmass, and it was confirmed by the filename of the picture.
The South Pole is towards the lower left corner. By visual inspection my best estimate for GP is roughly 17°S 132°W.
The height is challenging, it couldn't be too far from Earth, because Australia looks quite large compared to the whole visible disk. The latitude difference for Australia if roughly 20°, and this distance could be compared to the diameter of the visible disk. This ratio determines the distance of the observer. I set up my equations, but early in the morning (local time) couldn't develop a closed formula (I believe it must be possible: it is kind a parallax and distance to the horizon problem), so I solved with brute force using the goal seeker possibility in Excel.
I found it approx 2840 km above surface.
