Have you ever wondered how far the distance from New York City to London is? How about from New York City to Venice? Rome? The distance from one place on Earth to any other place on Earth is the great circle distance. The great circle distance is the distance from any two points on a sphere. The formula for distance is d = r ∆θ, where r is length of the sphere’s radius and ∆θ is the central angle between two given points.
Here is an interesting site that calculates distances from any two points on Earth.