Question

what is the importance of longitude

Answer 1

All lines of longitude are great circles, as well as the Equator, which is a line of latitude. ... Because lines of longitude are measured east or west of the Prime Meridian it is important to place an "E" or "W" after the degrees. Half way around the globe from the Prime Meridian is 180°

Answer 2

Time zones which exists today are all because of longitudes . Greenwich meridian passes through London and it is taken as origin GMT and rest of time zones are calcualted.If you move right side of GMT we add time and left side we subtract time.