I have chased, photographed, and oohed at rainbows my whole life and never once questioned a single thing about them. Big mistake. It turns out the cheerful arc in the sky is way stranger than the cartoon version — for starters, it’s not even an arc. Here are five facts that completely rewired how I look at a rainbow.
Did you know a rainbow is actually a full circle?
We only ever see the top slice of a rainbow, so we assume it’s an arc — but a rainbow is genuinely a complete circle. The reason you only see part of it is that the ground gets in the way; the bottom half of the circle is cut off by the horizon. Climb high enough — say, into an airplane — and you can actually see the whole thing as a perfect, unbroken ring of color floating below you. Pilots see them all the time. So every “arc” you’ve ever admired was really just the visible top of a circle you weren’t tall enough to finish.
Did you know nobody else can see your exact rainbow?
Here’s the one that genuinely broke my brain: the rainbow you’re looking at is yours and yours alone. A rainbow isn’t a physical object sitting in a fixed spot in the sky — it’s an optical effect created by sunlight bouncing through millions of raindrops at a precise angle relative to your eyes. The person standing ten feet away is seeing light from a completely different set of raindrops, which means they’re technically looking at their own personal rainbow. Even your two eyes see slightly different rainbows. You can stand next to someone and point at “the rainbow” and you are, scientifically, pointing at two different things.
Did you know there’s such a thing as a moonbow?
Rainbows don’t strictly need the sun — they just need a bright enough light source, and on a clear night the moon can do the job. The result is called a moonbow (or lunar rainbow), and it’s real, though rare. Because moonlight is so much dimmer than sunlight, our eyes usually can’t pick up the colors, so a moonbow tends to look ghostly white to the naked eye. But a long-exposure camera will catch the full spectrum hiding in there. They show up most reliably near big waterfalls and in places with very dark skies — and the first person to write about them was apparently Aristotle, so people have been squinting at them for over two thousand years.
Did you know a double rainbow’s second arc has its colors backwards?
When you spot a double rainbow, take a close look at the fainter outer arc — its colors run in reverse. The bright primary rainbow goes red on the outside down to violet on the inside. The secondary one flips it: violet on the outside, red on the inside. It’s not a glitch. The extra arc appears because some light bounces around twice inside each raindrop instead of once, and that second bounce literally turns the color order upside down. The double reflection also leaks away some light, which is why the second arc is always dimmer — and why the dark band of sky between the two arcs even has its own name: Alexander’s band.
Did you know you can never, ever reach the end of a rainbow?
Sorry to the leprechauns, but the pot of gold was never findable — because a rainbow has no fixed location to walk toward. Since the whole thing depends on the angle between you, the sun, and the raindrops, the rainbow moves the instant you do. Take a step toward it and it takes a step back, keeping that exact angle locked in forever. It’s not playing hard to get; it physically cannot stay put. And while we’re collecting weird rainbow types: there are red rainbows (only red survives when the sun is low at sunset), fogbows (almost colorless ghosts made by tiny fog droplets), and even “twinned” rainbows that split from a single base into two arcs. The sky has way more variety than the eight-crayon version we grew up with.
Send this to whoever in your life still thinks there’s a pot of gold at the end — gently explain why they’ll be walking forever.
