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Astrostudy1-SchA - STUDY GUIDE FOR ASTRONOMY 100 Schneider...

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STUDY GUIDE FOR ASTRONOMY 100, Schneider & Arny, Dr. Hedin 1. What is the definition of the astronomical unit (AU)? How is a “light-year” defined? How many light-years away is the nearest star? Average distance between the Earth and the Sun. How far light travels in one year.. The nearest star is 4.2-4.3 light years away- 2. What are the names of the planets in our solar system? What is a galaxy? Mercury, venus, earth, mars, Jupiter, Saturn, Uranus, Neptune, Pluto, eris, ceres A galaxy is a massive system of stars, gas, and dark matter held together by their mutual gravity. Typical galaxies have a mass between about 10^7 and 10^13 solar masses. The milky way is our galaxy, which is usually capitalized. 3. About how many stars are in a typical galaxy? How big across is our Milky Way galaxy? Is our galaxy part of any larger grouping of galaxies? The milky way galaxy has between 200-400 billion stars. 100 times the diameter. The milky way is part of a collection of galaxies called the local group. It is local, because it is one we inhabit. It contains 4 dozen galaxies with a 3 light year diameter. 4. Be able to express numbers in scientific notation, and be able to do simple unit conversions, given the conversion factor. 5. What is the scientific method? What makes a valid scientific theory? The procedure by which scientists construct their ideas about the universe and its contents, regardless of whether those ideas concern stars, planets, living things, or matter itself. Once a hypothesis has been thoroughly tested and verified, it may be termed a valid scientific theory or a law. 6. What force holds the planets in orbit? What force holds the electron in the atom? Gravity of the sun holds the planets in orbit.. electrons are attracted to the nucleus and protons. Their opposite charges attract each other. 7. Why are different constellations seen at different times of the year? A constellation is a recognized grouping of stars. because the earth orbits the sun, we are rotating and see different parts of the night sky each night. 8. As seen from Earth, in which directions do stars rise and set? Why does this happen? What are “circumpolar stars”?
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The stars that do rise do so in the east set in the west, just like the sun. It is because of the rotation of the earth. As is the case with the sun, the rising and setting of stars is an apparent motion and not a true motion; the sun and stars do not orbit around the earth. Depending on your location, some stars never go below the horizon. A circumpolar star is a star that, as viewed from a given latitude on Earth, never sets (that is, never disappears below the horizon), due to its proximity to one of the celestial poles . Circumpolar stars are therefore visible (from said
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