Units and Measures of the Federal Constellation

The Standards Coordinating Body (SCB) maintains an assortment of official units standards, collectively known as Constellar Units, used by the Constellation government. It was originally created as a compromise between the Constellation's founding members, which used separate systems. These standards are widely used in intersolar industry and trade for convenience. On planetoids where more traditional systems were used for generations, Constellar Units and the other measures are in mixed use.

Since the official number system in the Constellation is base-12, all units are based around this number system as well. There are various prefixes for units, such as kilo- as in kilochron for 12³ chrons. For some units like chrons, prefixes like myrio- (12⁴) are common, which may be unusual for those used to other nomenclatures.

The basic unit of time is the chron (approximately 970 seconds), defined as 12¹² periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133. This was chosen because caesium-133 exhibits properties that make it easy to construct reliable atomic clocks.

The basic unit of length is the tetra (approximately 3.26 cm), defined as the distance travelled by light in a vacuum in 1/12¹² chrons.