SU or "stellar unit" is a Colonial measurement of distance in space.
Examples of Usage
Lee Adama reports the distance of the missing Raptors from Pegasus in SUs (TRS: "The Captain's Hand").
Anastasia Dualla reports that the Rebel basestar jumped in at a range of 15 MSUs, apparently a subunit of SUs (TRS: "Guess What's Coming to Dinner").
Starbuck reports that tidal stresses around a black hole orbited by the Colony would destroy Galactica before it could come within 10 SUs (TRS: "Daybreak, Part I").
The final six digits of Galactica's jump coordinates represent its jump range in SUs, suggesting that the ship's maximum jump range - or at least the maximum inputtable distance - is 999,999 SUs (or 15.81 Colonial light-years).
- The real-world equivalent of the SU is the astronomical unit (AU), which is approximately equal to the distance between the Earth and the sun. Because distances in the Colonial star systems are very likely to be different, the SU cannot be assumed to have a value close to that of the AU. However, the relationship between the SU and the Colonial light-year (which would vary from ours based on the difference between the year of the Twelve Colonies' reference point - possibly Caprica's orbit around its star - and our own) is the same as that between AU and terrestrial light-years. Character ages in the series are similar to our own, suggesting that the differences between Earth and Colonial references are minimal, if not negligible.