J

Joule- A unit of energy in the mks system equal to 107 ergs, 1 Watt second, or 0.2389 calories.

Julian day- The number of days that have elapsed since 12 noon Greenwich Mean Time (UT) on Monday, January 1, 4713 BC in the proleptic Julian calendar (the day is counted as Julian day zero; the Julian day system was intended to provide astronomers with a single system of dates that could be used when working with different calendars and to unify different historical chronologies).