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A light-year, or light year, also abbreviated ly, was the distance light traveled in vacuum in one Galactic Standard Year. 3.258 light years made up a parsec, which was a unit of distance that was important in locating star systems in the known galaxy.[2]
Since the Galactic Standard Calendar year was 368 days, a Galactic Standard Light Year would have been 9,531,961,160,601,600 meters.
Behind the scenes
The above calculation assumes that the Galactic Standard Day, Hour, etc. and Meter are equal to Earth's, and results in an in-universe light year 0.75% longer than the real-world one.
It is also possible that Galactic days (and hours etc.) were 0.75% shorter than their Earth equivalents, and that the light years are the same length. (see below)
The length of a light year depends on the exact length of one year. On Earth, the International Astronomical Union (IAU) uses a Julian year of 365.25 days, while other sources may use a Gregorian year of 365.2425 days, or another year altogether.
| Source | year (days) | light year (meter) | light year (miles) |
|---|---|---|---|
| IAU | 365.25 | 9,460,730,472,580,800 | 5,878,625,373,184 |
| Gregorian | 365.2425 | 9,460,536,207,068,020 | 5,878,504,662,190 |
| 365.242199 | 9.460 528 4 ×1015 | 5.878 499 81 ×1012 | |
| Yahoo | 365.2411‡ | 9.460 5 ×1015 | 5,878,482,164,161 |
| Coruscant | 368 | 9,531,961,160,601,600 | 5,922,886,070,723 |
‡ While Yahoo separately reports a year length of 365.24220 days, its rounding of the light year length to five digits results in a year length of ~365.2411 days.
