Science

Lunar Halos, Septuple Rainbows and Iridescent Meat: Incredible Optics Photos

For 14 years, the website Optics Picture of the Day has collected and featured stunning examples of optical effects. We look at some of our favorites and the physics underlying them.
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  • Lightning Spectra
  • Iridescent Meat
  • Lunar Halo
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lightning-spectra
Sometimes you catch an odd glint of light, see a colorful rainbow or spot a hazy mirage in the distance. All these are optical effects, where a distortion of light produces some incredible image. Optics is the branch of physics dealing with the behavior of light, how it interacts with matter and the way it reflects from and refracts through materials. For 14 years, the website Optics Picture of the Day has collected and featured stunning examples of these effects. The site’s owner, physicist Les Cowley, came to appreciate what light can do one cold afternoon back in the 1970s. “I was dragged outside the lab to see an ice halo display,” he wrote in an e-mail. “The sky was webbed and crisscrossed with delicate arcs -- it was entrancing. I had no idea of their names or how they had formed but I was hooked on sky optics.” Cowley started OPOD back in 1998 to spread the message of sky optics and help explain how such phenomena form. Fairly soon, other interested photographers were submitting their own superb pictures. In this gallery, we look at some of the site's most amazing images and the physics underlying their eye-catching effects. Above:

Lightning Spectra

In his celebrated 1704 book Opticks, Isaac Newton describes shining a white light through a prism. When the light emerged, the famous physicist was surprised to see it broken into a dazzling rainbow of colors. While this and other discoveries from Newton helped revolutionize the field of optics, it wasn’t until the 1800s that scientists understood how much information those rainbows contained. When passed through a prism, the light coming from a hot gas reveals its constituent elements in telltale lines of color. In this image, taken during a thunderstorm over Paris, the forking lightning bolt heats surrounding air to between 36,000 and 54,000 degrees Fahrenheit, breaking apart air molecules into ionized plasma. The bright lines of the spectra reveals the presence of nitrogen and hydrogen in our atmosphere. Image: Denis Joye