Flying from Dallas to San Francisco on Monday, I looked out the window of the airplane and saw a rainbow.
OK, this isn’t my picture. I took some pictures of what I saw, but I don’t think they came out. My knowledge of cameras is purely theoretical – in other words, I can’t take a good picture to save my life. Besides that, I’m in San Francisco and don’t have a way of transferring pictures from the camera to my computer.
Anyway, what I saw, and what you see in the image above, is called a glory. What a great name! It’s essentially a rainbow seen from above. The Sun was on the opposite side of the plane from me, and the light of the Sun, bouncing back to my eye after its 93 million mile journey, was divided into its spectrum by the cloud.
Clouds are made of tiny drops of liquid water. They’re usually white because light that goes into a cloud normally bounces around inside like a pinball before returning to our eyes. As a result, all colors of light are on average scattered the same amount. But at the very top of a cloud, where drops are not so packed in, light beams can enter a single drop, bounce off the back, and enter right into my (or your) eye. Because different colors of light bend different amounts in passing from air to water (and water to air), the colors normally hidden in sunlight enter my eye at different angles. The result? Glory!
(By the way, this image shows what I saw, a double glory. This results from an extra reflection from some of the light, so that the colors in the second, outer, glory, are the reverse of the colors in the primary, inner glory. Glorious!)
But, in one of those wonderful, beautiful connections that make my heart sing, there’s more to the story. In 1911, a meteorologist named C.T.R. Wilson was at the Ben Nevis weather station on the Scottish mountain of the same name. He looked down onto the low-lying fog below him and saw what I saw, a glory at the top of the clouds. Wilson wondered if he could create a glory in the laboratory.
To create a glory, first Wilson needed a cloud. How to make a cloud in a laboratory? Wilson’s answer was to create a cloud chamber. He did so, and quickly forgot all about glories, because his cloud chamber revealed something even more amazing – pieces of atoms! Cloud chambers became the tool of choice for atomic physicists to study all manner of sub-atomic particles, and Wilson won the 1927 Nobel Prize in physics.
Today, physicists have moved beyond cloud chambers to more sophisticated detectors. The most advanced of these detectors – in many ways the most sophisticated scientific instruments ever constructed – are now to be found at the Large Hadron Collider in Europe. And this very day, scientists at the LHC are set to announce their first significant findings – discoveries that will forever change the way we see the world. If you follow the news out of the LHC (and I hope you do – you can bet I will), remember that it all started with glory.