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SYFY WIRE Bad Astronomy

Bad Astronomy Video: Rainbow Falls

By Phil Plait

A video of an astonished crowd at a restaurant overlooking Niagara Falls went semi-viral recently, showing a circular rainbow created by spray from the water. Seeing a circular rainbow is rare, since you need fairly particular circumstances for it.

Let me explain, in this week’s BA video!

In the video, I mention a bunch of different sciencey things, including Snell's law (how light bends when it passes from one medium to another, like from air to water and back again) and the anti-solar point (the spot in the sky directly opposite the Sun). If there's some other thing I mention that you've never heard of before, I encourage you to look it up! Chances are I've written about it before.

In the original Niagara Falls video, you can hear the crowd of people oohing and aahhhhing over the rainbow. I found their reaction delightful. I saw some comments on Facebook mocking the crowd in the restaurant, but that’s pretty mean-spirited, and worse, short-sighted. These people were seeing something they had never seen before and were curious about it. That is exactly the attitude I love to see!

Instead of making fun of them, we should be encouraging them to learn more about the wonders of the natural world, especially the ones we don’t expect. The science of rainbows is pretty cool, with some of it relatively simple and other parts—like supernumerary arcs—more complex.

And not to indulge in this too much, but I wonder if any of those commenters know about Alexander’s Dark Band, or all the wondrous and weird ice halo formations you can get in the sky, or any of a hundred other bizarre phenomena that can be witnessed when you look up.

We are all at different experience levels when we gaze at the sky, and no one knows it all. My own rule is simple: Look up, and always be delighted at the show the sky puts on for us. There’s room for everyone in the audience.

Watch more of Slate’s Bad Astronomy videos with Phil Plait.

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