Guest Post – Light Pollution: Where Careers Collide

Emma is one of my regular guest bloggers. I feel really thrilled about the possibility to post one educating post of this great blogger once a month over the next couple of months. Thank you so much, Emma, for sharing these great posts with us! If you would like to check out the previous guest posts, this amazing blogger wrote for me, head over here.


To a physicist, a lightbulb is a revolutionary science, and Thomas Edison is a hero. LEDs are especially revolutionary. Until recently, scientists only knew how to manufacture red and green LEDs. Red and green are cool colors and all, especially since they’re common holiday colors, but what scientists really wanted was white light. You get white light, and you can do anything with it. White light is composed of every single color (excepting brown—a pigment, and black—the absence of light), so if you have white light and a method of bending it to separate it into the individual colors, you can get every color of the rainbow and still more. The invention of a white LED would be an incredibly exciting discovery.

The heroes of LED light turned out to be Isamu Akasaki and Hiroshi Amano of the University of Nagoya and Shuji Nakamura from Nichia Chemicals, three Japanese researchers. They discovered new ways of growing specific crystals and mastered fresh techniques for controlling semiconductors. The result was an amazing feat of physics: blue LED light at the correct intensity to mix with the previously existing red and green and create a full spectrum.

As can be expected, the new white LEDs immediately became very popular. They occupy Christmas lights, television sets, and streetlights. White LEDs weren’t just exciting to the public, however. White LEDs opened up an opportunity for a whole new avenue of exploration in the field of physics. Physics, after all, is the branch of science that explains the properties of light. Previously, physicists could only use red and green LED light to hypothesize how LED light would behave all the way across the color spectrum. Now that white LEDs existed, physicists could abandon the theoretical and get to work on the tangible within their labs. LEDs became a public sensation and an opportunity for scientific discovery at the same time.

But not all scientists are happy with the turnout. Astronomers don’t thrive on experimental physics. In fact, back when physicists were forced to hypothesize and theorize about the nature of white LED light, astronomers thought the’d finally found an area of science where they and physicists stood on the same ground. Astronomers deal not in the physical world of the expected, but in the infinite world of the unexpected. There is so much we don’t know about space and the universe that astronomers’ concept of science is radically different from that of other scientific branches or the public. Astronomy is like any other science in that it deals in constant discovery, but it is one of the few sciences that deal almost entirely in the theoretical.

So why exactly did astronomers wince when a new discovery was made? Because the entire field of astronomy is based on the collection of as much light from space as possible. The problem with the light our civilization produces in order to see at night is that it leaks into astronomers’ view of the sky. Astronomers don’t have the right technology to filter out ever little photon of light that doesn’t come from a cosmic object, because they can’t afford to assume that any little photon won’t mean a new discovery of some unknown object beyond the reaches of our galaxy. They keep all the light they get, and they can never get enough of it. LEDs are very bright and easily reach astronomers’ telescopes at night, but the existence of only two colors of the spectrum wasn’t all that bad. But when white LED light came out, all of a sudden astronomers realized they couldn’t trust any one photon of light in the entire spectrum. The photons they collected from LEDs drowned out the light of the distant stars. Ironically, the invention of white LED light left astronomers blind.

There are many reasons to limit light pollution, but to explain it all would take up more space than I have here. Perhaps soon I’ll write more on the subject. In fact, I think I’ll have to.