The Many Lives of Null Island
A deep-dive into some hardcore mapping arcana. “Null Island” is not an island. It’s a term for “the coordinates of 0º latitude and 0º longitude, a location in the Atlantic Ocean off the coast of Africa where the Prime Meridian meets the Equator, hundreds of miles from any real dry land.”
Null Island is not just a silly place to think about when cartographers are bored, it is a phenomenon that repeatedly and annoyingly asserts itself in the middle of day-to-day cartographic work, often when you least expect it. Sometimes you load a new dataset into your GIS program, but the coordinates aren’t parsed correctly and they turn into all zeroes: your data is on Null Island. Or sometimes if the map projection file for your data is wrong, you’ll find a tiny scaled-down copy of your coordinates floating around Null Island. Or even worse, maybe most of your data is showing up in the right place, but only a few of your records are missing coordinates; if you don’t think to check for it, you won’t even realize that some of your data points have “taken a trip to Null Island.”
Let me try to explain with a few examples.
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