12. Theory of Time

Excerpt

In this chapter, concerning solar, sidereal and lunar time, are primarily for navigational officers holding or studying for specialist celestial navigation qualifications. Due to the advent of time systems based on atomic-standard clocks, computer programmes capable of instantaneous reduction of celestial navigation sights (see Chap. 3) and the withdrawal of the sidereal stopwatch (previously used for one variant of manual rapid sight reduction), a knowledge of solar, sidereal and lunar time is of less significance now than hitherto. However, solar time information is still extant in the maritime domain and is published in the daily pages of the Nautical Almanac. Implicit with their ‘expert’ status, it remains relevant for the navigation specialists to retain a knowledge of the astronomical factors involved in ‘time’ as part of their general understanding of the workings of the celestial sphere. The following paragraphs provide a readily available reference for this subject. …