Language & WorldHow it works
How to derive a place's time zone from its longitude.
Earth turns 360° in 24 hours, so 15° per hour. Ideal time zones are 15° wide, 7.5° either side of a central meridian, as Sandford Fleming proposed in 1876. Divide longitude by 15 and round: Berlin at 13° east gives +1. In practice governments push boundaries westward, so Spain, France and western China live hours away from the sun.
Useful: If longitude divided by 15 doesn't match the official time, the reason is politics, not geography.
Source: en.wikipedia.org