2010.02.12 08:46
20 Things About Light - L.Keany
2. Those photons from the big bang are still running loose, detectable as the cosmic microwave background. 3. Light moves along at full speed at 186,282.4 miles per sec only in a vacuum. In a dense matrix of diamond it slows to just 77,500 miles per sec. 4. Diamond's dazzling sparkle results from a lot of pinging back and forth of the photons in a thicket of carbon atoms to find an exit. 5. Eyeglasses can correct vision because light changes speed when it passes from air to a glass or plastic lens; this causes the rays to bend. 6. Plato fancied that we see by shooting light rays from our eyes. 7. Plato was not completely wrong. Like all living things, humans are bioluminscent. We glow. We are brightest during the afternoon, around our lips and cheeks. The cause is believed to be due to free radicals resulting from chemical reactions of our body. 8. Bioluminscence is the largest source of light in the oceans; 90 percent of all creatures who live below 1500 feet are luminous. 9. World War 2 aviators used to spot ships by the bioluminscence in their wakes. In 1954 Jim Lovell(later the pilot of Apollo 13) used this trick to find his darkened aircraft carrier. 10. Incandescent bulbs convert only 10% of the energy they draw into light, which is why Europe will outlaw them by 2012. Most of the electricity turns into unwanted heat. 11. In a confined space of oven, a 100 watt bulb can create a temperature of 325 degrees Fahrenheit. 12. Light has no mass, but it does have momentum. Later this year the Planetary Society will launch Lightsail-1, attempting to capture the pressure of sunlight the way a boat sail gathers the wind. 13. Laser beams bounced off mirrors left behind by Apollo austronauts show that the moon is moving away 1.5 inches farther from Earth each year. 14. Visible light makes up less than one ten-billionth of the electromagnetic spectrum from radio waves to gamma rays. 15. Goldfish can see infrared radiation that is invisible to us. Bees, birds, and lizards have eyes that pick up ultraviolet. 16. Photography means "writing with light." English astronomer John Herschel, whose father discovered infrared, coined the term. 17. Just after sunrise and before sunset produces the prettiest shadows and colors for photographs. 18. Day and night are everywhere the same length on the vernal equinox, which occurs on March 20. 19. Auroras light up the night sky when solar wind particles excite atoms in the upper atmosphere. Oxygen shines green; nitrogen blue and red. 20. But to the Inuits, auroras are spirits of the dead kicking around the head of a walrus. |
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As we get older, I feel that it is a good advice and
decided to put these science facts on our page to stimulate our curiosity once again.