longitude and time?

Question

i'm reading a book about longitude and how it helped sailors in the earlier times to sail. i don't understand how it helped them sail and like why it was important for them to know the difference in time at their original port and wherever they are at a specific time. k please help. thanx. i hope ppl understand my question.

Answer 1

Longitude is spaced on the surface of the Earth much like the hours of a day are spaced at any given moment in time. The Earth spins around once every 24 hours, so there are 24 different hours on the surface of the Earth at any time. By knowing the time sailors were able to plot their position by measuring the azimuth of the sun, which is the angle from the surface of the earth to the center of the sun. When correlated with the time of day, they can plot their position.

One more bit of info, sailor needed to know what time it was in Greenwich, which is in England. Since the English ruled the seas, they sort of made England the center of the Earth time wise. That way the sailors were able to compute their relative position with respect to Greenwich (Greenwich Mean Time comes from this practice for navigation).

Answer 2

each longitude is 4 minutes ie in one hr sun travells 12 longitudes thus in one day 12 * 24 =360 degrees.

Answer 3

towards EAST from 0 degree= minus 4 for each latitude
towards SOUTH from 0 degree=plus 4 for each latitude