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Amateur Astronomy

July 30th 2008 06:46
Astronomers use tools such as telescopes, cameras, spectrographs, and computers to analyze the light that astronomical objects emit. Amateur astronomers observe the sky as a hobby, while professional astronomers are paid for their research and usually work for large institutions such as colleges, universities, observatories, and government research institutes. Amateur astronomers make valuable observations, but are often limited by lack of access to the powerful and expensive equipment of professional astronomers.

A wide range of astronomical objects is accessible to amateur astronomers. Many solar system objects—such as planets, moons, and comets—are bright enough to be visible through binoculars and small telescopes. Small telescopes are also sufficient to reveal some of the beautiful detail in nebulas—clouds of gas and dust in our galaxy. Many amateur astronomers observe and photograph these objects. The increasing availability of sophisticated electronic instruments and computers over the past few decades has made powerful equipment more affordable and allowed amateur astronomers to expand their observations to much fainter objects. Amateur astronomers sometimes share their observations by posting their photographs on the World Wide Web, a network of information based on connections between computers.

Amateurs often undertake projects that require numerous observations over days, weeks, months, or even years. By searching the sky over a long period of time, amateur astronomers may observe things in the sky that represent sudden change, such as new comets or novas (stars that brighten suddenly). This type of consistent observation is also useful for studying objects that change slowly over time, such as variable stars and double stars. Amateur astronomers observe meteor showers, sunspots, and groupings of planets and the Moon in the sky. They also participate in expeditions to places in which special astronomical events—such as solar eclipses and meteor showers—are most visible. Several organizations, such as the Astronomical League and the American Association of Variable Star Observers, provide meetings and publications through which amateur astronomers can communicate and share their observations.
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Astronomy

July 26th 2008 22:44
Astronomy, study of the universe and the celestial bodies, gas, and dust within it. Astronomy includes observations and theories about the solar system, the stars, the galaxies, and the general structure of space. Astronomy also includes cosmology, the study of the universe and its past and future. People who study astronomy are called astronomers, and they use a wide variety of methods to perform their research. These methods usually involve ideas of physics, so most astronomers are also astrophysicists, and the terms astronomer and astrophysicist are basically identical. Some areas of astronomy also use techniques of chemistry, geology, and biology.

Astronomy is the oldest science, dating back thousands of years to when primitive people noticed objects in the sky overhead and watched the way the objects moved. In ancient Egypt, the first appearance of certain stars each year marked the onset of the seasonal flood, an important event for agriculture. In 17th-century England, astronomy provided methods of keeping track of time that were especially useful for accurate navigation. Astronomy has a long tradition of practical results, such as our current understanding of the stars, day and night, the seasons, and the phases of the Moon. Much of today's research in astronomy does not address immediate practical problems. Instead, it involves basic research to satisfy our curiosity about the universe and the objects in it. One day such knowledge may well be of practical use to humans.

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Refining the Theory Of Big Bang

July 25th 2008 13:40
Astronomers continue to make new observations that are also interpreted within the framework of the big bang theory. No major problems with the big bang theory have been found, but scientists constantly adjust the theory to match the observed universe. In particular, a “standard model” of the big bang has been established by results from NASA's Wilkinson Microwave Anisotropy Probe (WMAP), launched in 2001 (see Cosmology). The probe studied the anisotropies, or ripples, in the temperature of cosmic background radiation at a higher resolution than COBE was capable of. These ripples indicate that regions of the young universe were very slightly hotter or cooler, by a factor of about 1/1000, than adjacent regions. WMAP’s observations suggest that the rate of expansion of the universe, called Hubble’s constant, is about 71 km/s/Mpc (kilometers per second per million parsecs, where a parsec is about 3.26 light-years). In other words, the distance between any two objects in space that are separated by a million parsecs increases by about 71 km every second in addition to any other motion they may have relative to one another. In combination with previously existing observations, this rate of expansion tells cosmologists that the universe is “flat,” though flatness here does not refer to the actual shape of the universe but rather that the geometric laws that apply to the universe match those of a flat plane.

To be flat, the universe must contain a certain amount of matter and energy, known as the critical density. The distribution of sizes of ripples detected by WMAP show that ordinary matter—like that making up objects and living things on Earth—accounts for only 4.4 percent of the critical density. Dark matter makes up an additional 23 percent. Astoundingly, the remaining 73 percent of the universe is composed of something else—a substance so mysterious that nobody knows much about it. Called “dark energy,” this substance provides the antigravity-like negative pressure that causes the universe's expansion to accelerate rather than slow down. This “accelerating universe” was detected independently by two competing groups of astronomers in the last years of the 20th century. The ideas of an accelerating universe and the existence of dark energy have caused astronomers to substantially modify previous ideas of the big bang universe.

For me, one thing is for sure. Doing research is not an easy task. But I'm happy of sharing what I've known. I hope that these informations will help for those who are in need of these...
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The universe cooled as it expanded. After about one second, protons formed. In the following few minutes—often referred to as the “first three minutes”—combinations of protons and neutrons formed the isotope of hydrogen known as deuterium as well as some of the other light elements, principally helium, as well as some lithium, beryllium, and boron. The study of the distribution of deuterium, helium, and the other light elements is now a major field of research. The uniformity of the helium abundance around the universe supports the big bang theory and the abundance of deuterium can be used to estimate the density of matter in the universe.

From about 380,000 to about 1 million years after the big bang, the universe cooled to about 3000°C (about 5000°F) and protons and electrons combined to make hydrogen atoms. Hydrogen atoms can only absorb and emit specific colors, or wavelengths, of light. The formation of atoms allowed many other wavelengths of light, wavelengths that had been interfering with the free electrons, to travel much farther than before. This change set free radiation that we can detect today. After billions of years of cooling, this cosmic background radiation is at about 3 K (-270°C/-454°F).The cosmic background radiation was first detected and identified in 1965 by American astrophysicists Arno Penzias and Robert Wilson


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Still on The Big Bnag Theory

July 25th 2008 13:28

The big bang theory seeks to explain what happened at or soon after the beginning of the universe. Scientists can now model the universe back to 10-43 seconds after the big bang. For the time before that moment, the classical theory of gravity is no longer adequate. Scientists are searching for a theory that merges gravity (as explained by Einstein's general theory of relativity) and quantum mechanics but have not found one yet. Many scientists have hope that string theory, also known as M-theory, will tie together gravity and quantum mechanics and help scientists explore further back in time (see Physics: Unified Field Theory).
Because scientists cannot look back in time beyond that early epoch, the actual big bang is hidden from them. There is no way at present to detect the origin of the universe. Further, the big bang theory does not explain what existed before the big bang. It may be that time itself began at the big bang, so that it makes no sense to discuss what happened “before” the big bang


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History of Big Bang

July 25th 2008 13:22

The overall framework of the big bang theory came out of solutions to Einstein’s general relativity field equations and remains unchanged, but various details of the theory are still being modified today. Einstein himself initially believed that the universe was static. When his equations seemed to imply that the universe was expanding or contracting, Einstein added a constant term to cancel out the expansion or contraction of the universe. When the expansion of the universe was later discovered, Einstein stated that introducing this “cosmological constant” had been a mistake.

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Big Bang Theory

July 25th 2008 13:16

Big Bang Theory, currently accepted explanation of the beginning of the universe. The big bang theory proposes that the universe was once extremely compact, dense, and hot. Some original event, a cosmic explosion called the big bang, occurred about 13.7 billion years ago, and the universe has since been expanding and cooling.

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