ɔnðə sˈɜːfɪs əvə sfˈɪɹ, ðɪs ɪz ɹᵻplˈeɪst baɪ ðə dʒˌiːoʊdˈɛsɪk lˈɛŋθ ˈɔːlsoʊ kˈɔːld ðə ɡɹˈeɪt sˈɜːkəl lˈɛŋθ, wˌɪtʃ ɪz mˈɛʒɚd ɐlˈɔŋ ðə sˈɜːfɪs kˈɜːv ðæt ɛɡzˈɪsts ɪnðə plˈeɪn kəntˈeɪnɪŋ bˈoʊθ ɛndpˈɔɪnts ænd ðə sˈɛntɚɹ ʌvðə sfˈɪɹ.
On the surface of a sphere, this is replaced by the geodesic length (also called the great circle length), which is measured along the surface curve that exists in the plane containing both endpoints and the center of the sphere.