NATS 1745 : Navigation & Longitude.docx

• School: York University
• Department: Natural Science
• Course: NATS 1745
• Professor: Mary- Helen Armour

Document Summary

Vital importance in 17th and 18th century. Latitude runs east west (horizontally), with zero being at the equator, and 90 at the poles. Latitude can be found by measuring the angular height above the horizon. (north star is higher in north, lower in south) Longitude runs east west (vertically), with zero passing through greenwich england. Finding longitudes requires very accurate time keeping and tables of positions of objects in the heavens. 1600"s hipparchus proposes that longitude could be found by observing the difference in time between moon eclipses. (not accurate, lunar eclipses were rare) Galileo proposes that longitude could be found by observing the difference in time between. Jupiter"s moon eclipses. (accurate observations required, successful on land, difficult aboard ship) Globe is a 360 degrees, 24 hours/day, 15 degrees of longitude would correspond to1 hour of time difference. Local time would be compared to a standard time (greenwich, uk became 0 .