Millions of metric tons of plastic wash into the sea each year, and studies have shown that we simply don’t know where the vast majority of it is. The corrosive forces of the ocean break these bottles, cigarette lighters and pieces of packaging down into tiny fragments that are difficult to track, but scientists have come up with a technique that could reveal their whereabouts by way of a glowing fluorescent dye.

Microplastics can measure as little as the width of a human hair, and one recent study estimated there to be somewhere between 93,000 and 236,000 metric tons of the stuff floating around on the surface of the ocean. Sure, that’s a lot, but the scientists behind that study estimate that it accounts for just one percent of the total plastic waste in the ocean, so where is the rest of it? Erik van Sebille, the lead author on that study, told us earlier in the year that it’s a bit like astronomers dealing with the unknowns of dark matter.