Calculating the International Date Line Crossing Between Hawaii and Okinawa

Step-by-Step Method

1. Convert coordinates to decimal degrees:
   • Hawaii: (21.3089° N, 157.8273° W) → (21.3089, -157.8273)
   • Okinawa: (26.3150° N, 127.7488° E) → (26.3150, 127.7488)
2. Longitude difference: 127.7488 - (-157.8273) = 285.5761° (exceeds 180°, so crosses the 180th meridian).
3. Midpoint longitude: (127.7488 + (-157.8273)) / 2 = -2.4863°.
4. Draw great-circle path: On a globe/map, the great-circle route between the two points passes through the midpoint longitude.
5. Find 180th meridian crossing: The point where this great-circle path crosses the 180° meridian is the exact International Date Line crossing between Hawaii and Okinawa.

This method uses spherical geometry to pinpoint the date-line intersection.