Longitude and Time

Rotation of the Earth is from the West to East and it takes 24 hours to rotate once covering 360°. Therefore, it takes one hour to cover a distance of 15°. It then means that time changes by one hour for every 15° of longitude. The Greenwich meridian is the reference longitude from which time is easily calculated.

Therefore, for every distance of 15°, 1 hour is covered. If a particular time is assigned to the Greenwich Meridian which is 0° longitude, it’s easy to assign an accurate time to a place in the east or west of the Greenwich. Again, if the time of a particular longitude is provided or known, one can calculate the time of another longitude, east or west of that longitude that has a time attached to it.