Word: sunlights
(lookup in dictionary)
(lookup stats)
Dates: all
Sort By: most recent first
(reverse)
Heat Balance. To make observations beyond the earth's atmosphere, the instruments in a satellite must be kept fairly cool. The job is harder than it sounds. Space is neither hot nor cold, but an object exposed to sunlight in space may get pretty hot. The temperature that it reaches will depend on how its surface absorbs and emits radiation. If the energy that it absorbs from sunlight is greater than the energy that it emits as heat rays, the body's temperature will rise. The amount of heat rays that it emits will rise too. Eventually...
...that 1) does not absorb much solar energy, and 2) gets rid of the energy that it does absorb without becoming too hot. When the satellites came from their manufacturer, Brooks & Perkins, Inc. of Detroit, they were thin-skinned magnesium spheres plated with gold. Aluminum is better for reflecting sunlight, but since aluminum will not stick to gold, the gold had to be covered with a thin film of chromium. Aluminum will stick to chromium, but it also mixes with it and loses part of its reflecting power. So the chromium film in turn had to be coated with glassy...
...arranged in flat disks like piles of plates. Biologists suspected that this delicate laminated structure had something to do with photosynthesis, but they could not make sense out of it until Bell Telephone Laboratories invented its solar battery, an electronic device made of thin layers of treated silicon. When sunlight hits the battery, it knocks electrons out of one of the silicon layers. Caught by another silicon layer, the electrons turn into a useful electric current. Hearing about this principle, Dr. Calvin and other scientists speculated that the thin layers of chlorophyll might capture light energy in somewhat the same...
...prove the theory. Researcher Calvin spelled out a delicate test: searching for free electrons in laminated chlorophyll exposed to sunlight. B. Commoner, J. J. Heise and J. Townsend of Washington University at St. Louis were the first to offer evidence that such electrons exist, but critics did not accept their experiment as conclusive. It was performed at room temperature, and under such conditions many chemical processes having nothing to do with photosynthesis can produce free electrons...
...yielding chemical reactions could not happen. Then they placed deep-frozen chlorophyll in a magnetic field and shot extremely high-frequency radio waves through it. When strong light was shone on the chlorophyll, some of the radio energy was absorbed. This proved to Dr. Calvin that chlorophyll exposed to sunlight contains free electrons, and is therefore capturing light energy by the layer-to-layer method. Nature's green plants. Dr. Calvin believes, have turned out to be electronic solar batteries invented millions of years before human scientists ever thought of electronics...