The galactic standard calendar, also known as galactic standard time, was a common standard for measuring time across the galaxy, regardless of the local differences. It was based on the orbital motion of the planet Coruscant.
The standard units of time were based on the orbital motion of Coruscant, and one of its moons.
The galactic standard calendar was a lunisolar system based on natural periods derived from observing the orbital cycles of the galactic capital, the planet Coruscant.
Its fundamental unit, the standard day, was based on one complete revolution of Coruscant. There were twenty-four hours in a day and five days in a standard week. It took 365 days for Coruscant to make a complete orbit of its star, Coruscant Prime, a time period that became the standard year. The year was divided into standard months and standard weeks. There were twelve months in a galactic year. No leap years existed in the calendar.
The five days in a standard week were, in order:
The galactic standard calendar was introduced under the Old Republic. Although some cultures kept measuring time in units other than those used by the standard, the system came to be understood in most places.
Millennial Celebration Invitation, a poster designed by the artists Naveela Betuine and Dashira Dobeq at the request of Supreme Chancellor Finis Valorum of the Galactic Republic, contained a line written in Aurebesh, which read "galactic standard time to be announced."
Star Wars: Build the Millennium Falcon 61 gives information on the Coruscant calendar that contradicts most sources. According to it, the planet took 368 standard days to make one complete orbit of Coruscant Prime. The length of a month, 35 days, was determined by the syzygy of Coruscant's primary moon Centax-1—the time it took to pass from one new (or full) moon to the next. The month was divided into seven weeks, each containing five days named after celestial bodies or historical inhabitants of Coruscant: Primeday, Centaxday, Taungsday, Zhellday, and Benduday. This 35 day and seven week numbering cannot be possible mathmatically given the twelve month and 365 day year.
Further according to Build the Millennium Falcon, there were 10 standard months in a standard year, which only added up to 350. Therefore, the "missing" 18 days were made up of three festival of fete weeks, plus three regular annual holidays. New Year Fete Week fell in the first five days of the new year, before the first month, while the Festival of Life fete occurred between the sixth and seventh, and the Festival of Stars between the ninth and tenth. The three holidays varied depending on the local culture. For example, Boonta Eve and Harvest Day were only observed on Tatooine.
- Star Wars: Absolutely Everything You Need to Know
- Star Wars: Build the Millennium Falcon 61
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- Star Wars: Absolutely Everything You Need to Know, Updated and Expanded