Exam 1 Study Sheet - Earth Wind Fire Exam 1 Study Sheet...

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Earth, Wind & Fire Exam 1 Study Sheet Spring 2007 Unit II Time and the Universe Important items or questions: From Unit II, Topic 1: Origin of the Universe What is the evidence for the Big Bang theory for formation of the Universe? The Universe is expanding Background Radiation About how old is the Universe? 13-14 billion years What process makes the Sun hot? It generates its energy by nuclear fusion of hydrogen nuclei into helium What are the basic differences between the Inner and Outer planets? Inner terrestrial planets: (Mercury, Venus, Earth, Mars) Small Dense – rock and metallic elements (Fe, Ni) High temperature Outer Jovian Planets: (Jupiter, Saturn, Uranus, Neptune, Pluto) Large, with small central rock cores Low density, gaseous – mainly H, He, ammonia, methane Low temperature (frozen) What are the four basic forces of nature? i. Gravity ii. Strong nuclear force iii. Weak nuclear force iv. Electromagnetic force How did galaxies form? You need to know the processes involved. 1. 4 basic forces of nature separate, most of expansion occurs 2. In the first 3,000 years it is made up mostly of energy 3. After 3,000 years it is made up mostly of matter, temperature drops 4. After ~200,000 years galaxies and stars form leads to gravity attraction pulling together some clusters and some less dense areas What is a galaxy? What is our home galaxy called? A galaxy is a massive, gravitationally bound system that consists of stars, and interltellar medium of gas and dust, and dark matter. Ours is the Milky Way and it formed about 4.6 billion years ago. Evolution of a sun or star – know the stages and reasons for changes
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FYI: a star is a massive, luminous ball of plasma. Stars group together to form galaxies, and they dominate the visible universe. The nearest star to Earth is the Sun. A star shines because nuclear fusion in its core releases energy which traverses the star’s interior and then radiates into outer space. Astronomers can determine the mass, age, chemical composition and many other properties of a star by observing its spectrum, luminosity and motion through space. Stars are formed within molecular clouds, they consist mostly of hydrogen, with about 23-28% helium and a few percent heavier elements. 1. The formation of a star begins with a gravitational instability inside a molecular cloud, often triggered by shockwaves from supernovae or the collision of 2 galaxies (as in a starburst galaxy) 2. Once a region reaches a sufficient density of matter it begins to collapse under its own gravitational force 3. As the cloud collapses, individual conglomerations of dense dust and gas form what are known as Bok globules. 4. As a globule collapses and the density increases, the gravitational energy is converted into heat and the temperature rises 5. When the protostellar cloud reaches the stable condition of hydrostatic equilibrium, a protostar forms at the core. The period of gravitational contraction lasts for about 10-15 million years.
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