birth and death of a star essays

birth and death of a star essays The night sky, unimaginably deep, is a breathtaking sight. Some three thousand stars can be seen with the naked eye, twinkling points of light that have inspired the human spirit since the dawn of time. Study of the stars, based on data collected from visible-light telescopes, radio telescopes, and detectors wavelengths can now reveal extraordinary amounts of information: size, temperature, chemical composition, internal structure, distance and rotation rate, among other factors. One of the most important discoveries that scientists and astronomers have made is mapping out the life cycle of a star. Little by little, they have discovered all the different stages of a star; from its birth to its eventual death. As giant molecular clouds orbit the center of a galaxy, they are tugged by gravitational and magnetic fields. How fast their constituent particles move depends on their temperatures: the colder the cloud, the slower the particles. Fast moving particles resist collapsing together, and so stars can form only in the dense cores of cold clouds. Typically, these clouds are only about 15 degrees above absolute zero. Periodically, the clouds begin to collapse. The trigger mechanisms for such collapses are thought to be collision between giant molecular clouds or entry onto galactic spiral arms. Both of these occurrences set up compression waves within the cloud, which cause isolated regions to become so dense that gravity overwhelms all other processes and the could collapses. These isolated regions can often contain enough mass to create several hundred stars of similar mass to the sun. They are known as Barnard objects, and often appear as black regions in front of stars. Sometimes regions with emission nebulas reach the appropriate density and collapse. These appear as round, black bubble within the glowing gas. They are referred to as Bok globules. As Barnard objects and Bok globules collapse, isolat...

Learn the Pros and Cons of Ethanol and Its Production

Learn the Pros and Cons of Ethanol and Its Production Ethanol is simply another name for alcoholthe liquid made from the fermentation of sugars by yeasts. Ethanol  is also called  ethyl alcohol  or  grain  alcohol  and is abbreviated as EtOH. In the context of alternative fuels, the term refers to an alcohol-based fuel that is blended with gasoline to produce a fuel with a higher octane rating and fewer harmful emissions than unblended gasoline.  The chemical formula for ethanol is CH3CH2OH. Essentially, ethanol is ethane with a hydrogen molecule replaced by a  hydroxyl radical,OHwhich is bonded to a  carbon atom. Ethanol Is Made from Grains or Other Plants No matter what it is used for, ethanol is produced by processing  grains such as corn, barley, and wheat. The grain is first milled, then fermented with yeast in order to transform the grains starches into alcohol. A distillation process then increases the ethanol concentrations, such as when a liquor distiller refines whiskey or gin through a distilling process. In the process, waste grain is produced, which is usually sold as livestock feed. Another by-product, the carbon dioxide produced,   can be used in other industrial applications.  Another form of ethanol, sometimes called bioethanol, can be made from many types of trees and grasses, although the fermentation and distilling process is more difficult. The United States produces close to 15 billion gallons of ethanol a year, mostly in states close to large-scale corn growing centers. The top producing states are, in order,   Iowa, Nebraska,   Illinois, Minnesota, Indiana, South Dakota, Kansas, Wisconsin, Ohio and North Dakota. Iowa is by far the largest producer of ethanol, producing more than 4 billion gallons a year.   Experiments are underway on the possibility of using sweet sourgum as a source of fuel ethanol, which can be grown with only about 22% of the irrigation water required for corn. This may make sourgum a viable choice for regions with water shortages.   Blending Ethanol with Gasoline Blends of at least 85 percent ethanol are considered alternative fuels under the Energy Policy Act of 1992. E85, a blend of 85 percent ethanol and 15 percent gasoline, is used in flexible fuel vehicles  (FlexFuel), which are now offered by most major auto manufacturers. Flexible fuel vehicles can run on gasoline, E85, or any combination of the two. Blends with more ethanol, such as E95, are also premium alternative fuels. Blends with lower concentrations of ethanol, such as E10 (10 percent ethanol and 90 percent gasoline), are sometimes used to increase octane and improve emissions quality but are not considered alternative fuels. A good percentage of all gasoline sold now is E10, containing 10 percent ethanol.   Environmental Effects A blended fuel like E85 produces less carbon dioxide, the single most important greenhouse gas responsible for climate change. In addition, fewer volatile organic compounds are emitted by E85.   Ethanol  is not without its environmental risks, however, because when burned in internal combustion engines, it produces significantly more formaldehyde and other compounds that can increase ground levels of ozone.   Economic Benefits and Drawbacks Ethanol production supports farmers by offering subsidies to grow corn for ethanol, thereby creating domestic jobs. And because ethanol is produced domestically, from locally grown crops,   it reduces U.S. dependence on foreign oil and increases the nation’s energy independence On the flip side, growing corn and other plants for ethanol production requires a lot of farmland, monopolizing fertile soil which instead could be used to grow food that might feed the worlds hungry. Corn production is especially needy in terms of  synthetic fertilizer and  herbicide,  and it frequently leads to  nutrient  and  sediment pollution. According to some experts, the production of corn-based ethanol as an alternative fuel  may end up requiring  more energy than the fuel can generate, especially when counting the high energy costs of synthetic fertilizer production.   The corn industry is a powerful lobby in the U.S., and critics argue that corn-growing subsidies are no longer aiding smaller family farms, but are now mostly of benefit to the corporate farming industry. They argue that these subsidies have outlived their usefulness and perhaps should be spent on efforts that more directly affect the public welfare.   But in a world of dwindling fossil fuel supplies, ethanol is an important renewable alternative which most experts agree has virtues that outweigh its drawbacks.