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How a monarch butterfly flies 4,000 kilometers — but lives for 6 weeks

In the fall, when it gets cold in Canada, millions of orange monarch butterflies take to the skies and begin flying south. They fly to Mexico — 4,000 kilometers away. That's farther than from Kyiv to Paris and back.

And now the most amazing thing: a single monarch butterfly lives only 6 weeks. It physically cannot fly all the way. So the journey is made by different generations. The butterfly that flies out of Canada is the great-great-great-grandson of the one that will return next year. None of them have ever seen the route. But they all know where to fly.

Scientists have long wondered how this is possible. It turns out that a butterfly's head has something like a compass that orients itself to the sun. And it also has an internal clock. Together, they work as a tiny navigation system that's more accurate than the GPS in your parents' phone.

When millions of monarchs arrive in Mexico, they cling to the trees in the mountains—so many that the branches break under the weight. From a distance, the trees appear orange, as if on fire. Locals call it a miracle.

A monarch's wing weighs less than a rose petal. But that tiny wing covers a distance that you would only fly by plane. So the next time you see a butterfly, remember: Maybe its lineage includes travelers who knew their way around without a map.