Observer's Longitude

Observer's longitude refers to the east-west position of a specific location on Earth's surface. It’s measured in degrees, with zero degrees at the Prime Meridian in Greenwich, England. Moving east or west from this line, longitude increases up to 180 degrees. Longitude helps determine local time and position relative to other places worldwide. For example, if you're at 30°E, you're 30 degrees east of Greenwich; if you're at 30°W, you're 30 degrees west. Together with latitude (north-south), longitude specifies an exact point on Earth, important for navigation, mapping, and timing.