South America lies entirely in the Western Hemisphere, so every part of the continent sits west of the Prime Meridian.
Where exactly does the Prime Meridian run?
Picture a line drawn straight down the middle of the Earth at 0° longitude. That’s the Prime Meridian. It starts at the North Pole, cuts through Greenwich, England, then heads south through western Europe and Africa. After grazing Antarctica, it finally reaches the South Pole. Royal Museums Greenwich calls this the official zero point for measuring longitude—everything else is measured east or west from here.
Quick facts to remember
| Fact |
Measurement |
| Prime Meridian longitude |
0° |
| South America’s westernmost point |
Ponta do Seixas, Brazil (≈ 34.79° W) |
| South America’s easternmost point |
Cabo Orange, Brazil (≈ 34.78° W) |
| Antarctica overlap |
Both hemispheres |
Why should you care about the Prime Meridian?
The Prime Meridian isn’t just some random line on a map—it’s the foundation of global timekeeping. Every time zone on Earth is calculated as an offset from 0° longitude, and Coordinated Universal Time (UTC) is based right in Greenwich. Time and Date points out that when it’s noon in London, it’s about 9 AM in São Paulo and 8 AM in Buenos Aires. Both cities? Solidly west of the Prime Meridian.
How do the hemispheres actually work?
Imagine slicing the Earth in two directions. The Equator (0° latitude) splits the planet into Northern and Southern Hemispheres. Meanwhile, the Prime Meridian (0° longitude) and its opposite, the International Date Line (180° longitude), divide the Earth into Eastern and Western Hemispheres. South America stretches from roughly 12° N in Colombia all the way down to 55° S in Chile. Every single square kilometer of the continent? West of the Prime Meridian. Even the Falkland Islands, sitting at about 51° W, are squarely in the Western Hemisphere.
Want to stand in two hemispheres at once?
Here’s a fun little geography hack: visit the Royal Observatory in Greenwich. Right there in the courtyard, a shiny steel line marks the Prime Meridian. You can literally straddle it—one foot in the Eastern Hemisphere, one in the Western. (No time-travel portal included, unfortunately.)
