Longitude is measured up to 180° east or west of Greenwich.
A meridian is a half-circle that connects the Earth's poles. Unlike lines of latitude (parallels), which vary in length and never meet, all meridians are of equal length and intersect at the poles. meridians longitude
Whether you are checking a world clock or pinning a location on a digital map, you are using a system of meridians that has guided human exploration for centuries. Longitude is measured up to 180° east or west of Greenwich
If there is a downside to longitude, it is the difficulty of calculation. it is the difficulty of calculation.