[banana_giraffe]

Assuming a spherical earth, it's 4873 km.

[foobar1962]

Assuming a spherical earth in a vacuum... One of the few times that simplifying assumption matches reality.

[kelnos]

Not quite; the Earth is an oblate spheroid. Assuming it's a sphere is certainly a close enough approximation for this exercise, though.

[dylan604]

How far is it if you assume a flat earth?

[hulahoof]

5000km