Japan Standard Time

The International Meridian Conference held in 1884 set the meridian that passes through the Greenwich astronomical observatory as the standard for longitude and determined that each country would use a time system that had a one-hour time difference at each 15° longitude interval. Japan also accepted this decision and set the time of 135° east longitude as Japan Standard Time in 1886. This system was put into practice from January 1, 1888.

In 1910, a meridian symbol was established in Akashi, Hyogo Prefecture. The Akashi municipal planetarium built in 1960 is located at the passage point of 135° east longitude. Japan Standard Time is nine hours ahead of Greenwich Standard Time (eight hours during daylight saving time).