GEK1506 Heavenly Mathematics & Cultural Astronomy, Tutorial 10

1. Why do we need an international date line? Why does the international date line go through the Pacific?
2. In order to win the £20,000 prize, Harrison had to determine longitude to within half a degree after a trip to the West Indies. If we estimate that it would take about 40 days to sail to the West Indies, what was the maximal daily error the clock could have?
3. You measure the altitude of the Sun to be 68.5° as it crosses the southern part of the meridian on the June solstice. What is your latitude?
4. On Valentine's Day, February 14, you see that the Sun crosses the meridian at 05:15 UTC. What is your longitude?