The table below shows the results of the following experiment.
1. Choose a pair of cities, and take the lat/long of a point in each. (cols 1-6)
2. Use the
haversine formula to compute the distance between those points. This implicitly uses the assumption that the world is approximately spherical. (Col 7)
3. Then enter the first lat long pair into the window of Google maps. Google understands that these are lat long coordinates, and marks a red point on the map. Right click on that point, and select ‘measure distances’. Enter the second pair, which takes you to the next place, then left click on the red marker. A window opens giving you the distance in km or miles. (Col 8 )
The results clearly indicate that Google maps is using round earth assumptions. So the question is whether Google maps is accurate or not. If it is, then the earth is approximately a sphere. If not, then not.
See my other experiment which was an attempt to correlate Google/Haversine with flight times.
City 1, City 2, Lat 1, Long 1, Lat 2, Long 2, Haversine, Google
Sydney, Melbourne, -33.87, 151.21, -37.81, 144.96, 713.43, 713.39
Frankfurt, Warsaw, 50.11, 8.68, 52.23, 21.01, 890.12, 890.15
New Delhi, Singapore, 28.61, 77.21, 1.35, 103.82, 4142.49, 4142.33
Mumbai, Cairo, 19.08, 72.88, 30.04, 31.24, 4358.21, 4357.79
Perth, Auckland, -31.95, 115.86, -36.85, 174.76, 5346.63, 5346.38
London, Perth, 51.51, -0.13, -31.95, 115.86, 14478.80, 14478.92