Globe Coordinate Prediction

[MrHalsey]

Hello my fellow excel people,

I'm trying to predict latitude and longitude coordinates within 2 predefined points. If this was a 2D problem then I'm sweet, but it gets tricky with the curvature of the earth (anti flat earther).

Once point A & B have been set i want to basically be able to predict as many in between points as i wish.

An example being i want a total of 11. This bit i have nailed, but just adds complexity.

What I'm struggling with is taking the earth curvature into consideration. Technically i find the midpoint but when I plot it onto a map it doesn't follow the correct logic.

I have a calculation for latitude and one for longitude. No difference just the reference. The example will only show 1 as its the same.

Obviously i have to factor in the earths radius - 6,371KM. Found lots online but nothing specifically for excel.

Heres a short file to visually see.

Point A	Point B
LAT A	-13.90061	LAT B
LON A	-137.50836	LON B
Point	LAT	Formula
1	-13.90061	=C3
2	-14.031651	=C8-((C$3-F$3)/10)
3	-14.162692	=C10-((C$3-F$3)/10)
4	-14.293733	=C12-((C$3-F$3)/10)
5	-14.424774	=C14-((C$3-F$3)/10)
6	-14.555815	=C16-((C$3-F$3)/10)
7	-14.686856	=C18-((C$3-F$3)/10)
8	-14.817897	=C20-((C$3-F$3)/10)
9	-14.948938	=C22-((C$3-F$3)/10)
10	-15.079979	=C24-((C$3-F$3)/10)
11	-15.21102	=F3

Using google mymaps we can visually see my predicted coordinates (navy) verses a correct line (red), additionally a middle point (green). Here we can see the inaccuracy of my results.

Overall, i need a formula to align my predictions with the correct line (red). Ideally in a single formula.

Thanks advance with the help.

If you require more info/explanation please say.

M