The orthodromic distance (distance between 2 points on a sphere).
The distance between Genova (44° 24' N, 8° 56' E) and Sydeny (33° 52' S, 151° 12' E). Earth radius is about 6370 km.

(I turn 60s into cents: 56 → 93, …;   33° S → − 33)

The distance between Genova and Sydeny is 16600 km.