From the July 2013 issue

Galaxy vs. home lighting

September 2013: While standard bulbs are phased out, one replacement produces light that doesn't occur naturally in the universe.
By | Published: July 22, 2013
Astronomy revolves around light. Some celestial objects emit a single dominating color, like green from ionized oxygen. This paints our eyepiece views of planetary nebulae like the Cat’s Eye (NGC 6543). But much more common is to see a mixture of colors.

If the blend is overwhelmingly green and red light, the object appears yellow. Add blue to that mix, and our eyes’ architecture perceives white. Throw in extra colors like orange and violet, and it’s still white.
Stars emit a rainbow spectrum of colors. Galaxies, made of stars, do the same. So do the Sun, some nebulae, and common incandescent light bulbs. They all appear white, though some stars offer a pastel patina of orange or blue when particularly rich in long or short wavelengths. If you own a spectroscope, which reveals the actual colors in any light, you see all this at a glance.

What a pocket spectroscope does not show is that natural sources, from stars to bulbs, also emit large amounts of infrared radiation, which our skin senses as heat. And therein lies the problem. Ordinary light bulbs produce far more heat than visible light. This isn’t too bad in winter, when they help warm the house. But in summer, this energy is doubly wasted because the unwanted heat makes air conditioners work harder. Moreover, like the Sun, those bulbs emit “extra” colors like yellow and violet — not needed if all you want is white created with maximum efficiency.

Here on Earth, many countries are switching to new types of bulbs, mostly compact fluorescent lamps (CFLs). They save energy compared with standard round light bulbs, which are being phased out by federal law. Already, companies can no longer manufacture 100- or 75-watt bulbs in the U.S. The same fate will befall 60W and 40W bulbs next year.

CFLs, whose glow comes from the electrical excitation of mercury vapor, a process unseen in nature, emit narrow wavelengths of red, green, and blue. They produce almost no infrared radiation, which is why they’re much cooler to the touch. No wonder a mere 15W bulb can create the same white intensity as an old-fashioned 60W one. So, if we want to reduce electrical generation, nearly 40 percent of which comes from filthy coal, forcing everyone to switch to CFLs and light-emitting diode (LED) lighting is a great idea.


There is one possible problem, however. The white light, though it looks the same, is very different from what illuminates our sunlit meadows, moonlit beaches, and the galaxy’s billions of planets. Should this matter?

Some evidence reveals that light affects health. For example, two independent epidemiological studies show that breast cancer is strongly correlated with women whose lifestyles deprive them of nightly darkness. The mechanism appears to be melatonin blood levels, which are normally low by day and high by night. Exposure to light, any light, suppresses the nocturnal production of melatonin by the pineal gland. In people who work night shifts or whose job or home location keeps them illuminated around the clock, the body never gains normal melatonin levels. Bottom line: Sleep in a dark place. If you live in a bright city, close those curtains.

So light can powerfully affect us. Which brings us back to the CFLs. They save energy. But they bathe us and our children, who are now surrounded by this light at school and at home, with a concoction nature produces nowhere in the universe. Astronomers, of all people, can see this firsthand.

Health consequences may not show up for decades. And there may be no deleterious effects when all is said and done. (LEDs are better; though they emit negligible infrared, they give off a greater range of colors than fluorescents.)
Our bodies evolved over millions of years exposed only to full-spectrum lighting such as sunlight, starlight, campfires, candles, and those standard bulbs. We should at least be aware of the odd witch’s brew emanating from the new lamps.

Here’s what I did. I bought boxes of 60W and 75W incandescent light bulbs (they’re still available), and now I have enough to last forever. I use them in the winter because their extra heat is not wasted energy during the cold season. In summer, when our bodies get many hours of natural light anyway, I switch to CFLs.

I honestly don’t know if I’m being paranoid. I’m not advocating anything here. But if you buy a good pocket spectroscope online (about $50), which is a wonderful astronomical tool, you’ll see exactly what’s going on.

We all want to save energy. Making your home lighting match the Sun and stars by “going for more colors” could create a conflict between hazy health concerns and societal benefit. Oh, well.

Life is rarely black and white.

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