... We flat earthers are scientists not accepting the magic...
Simple question for a scientific mind:
Distance from North pole to Equator is 10 000 km. It is measured.
Circumference of Equator is 40 074.5 km. Also measured.
A scientist will know the formula for circumference of a circle.
Why circumference of Equator is not 62832 km? 
Simple. circumference in Equator isn't the longest line compared the outer circles.
Distance from North pole to Equator is measured. It is
10 000 km.
That is how Metre was defined in the first place. It was in France in 1789.
A new unit of length, the metre was introduced - defined as one ten-millionth of the distance from the North Pole to the equator.
(from:
https://en.wikipedia.org/wiki/History_of_the_metre)
Measuring circumference of Equator can be done by measuring ground speed of subsolar point for Equinox.
Sun (and subsolar point) will not look for any straight-line shortcuts, it will follow Equator all day.
That's where the result of
40 074.5 km came from.
Now please tell us what would outer circles have to do with it?
~~~~~
EDIT: There are two places in Indonesian island Kalimantan.
The places are both on Equator.
Bontang is at 117.48 degrees east.
Pontianak is at 109.34 degrees east.
The longitude difference is
8.14 degrees.
For the need of Indonesian government many distances are measured, including the distance between these two places.
The distance between Bontang and Pontianak is
906.13 km.
Knowing that Sun travels 15 degrees per hour, we know that those 8.14 degrees will pass in 0.542667 hours.
It will give us ground speed of subsolar point to be 1669.77 km/h.
That's right:
1669.77 km/h times
24 h gives circumference of Equator to be 40074.5 km.
(If 8.14 degrees is 906.13 km, how much is 360 degrees?)
