hw 1 astronomy - Jennifer Jacob Phys 180 September 9, 2011...

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Jennifer Jacob Phys 180 September 9, 2011 Homework due 9/15/11 1. A geocentric universe is the idea that the earth is the center of the universe and everything in the universe revolves around the earth. Our modern universe is more detailed than that idea. Earth orbits the sun and everything in our universe moves relative to one another. 2. A star is a large glowing ball of gas. A planet is large enough for its own gravity to make it round, orbits a star, and has cleared most other objects from its orbital path. A galaxy is a great island of stars in space all held together by gravity and orbiting a common center. A galaxy contains a few million to a trillion or more stars. 3. Over time, the average distance between galaxies increases. The big bang is about 14 billion years ago when the universe was born before expansion started occurring. 4. When Carl Sagan said we are “star stuff”, it is because our planet is made of elements manufactured from stars from nuclear fusions that make stars shine and nuclear reactions accompanying explosions that end the life of stars. 5. A light year is the distance that light can travel in one year. One light year is equivalent to 9.46 trillion km. The speed of light is 300,000 km/s. 6. If we look at a galaxy that is 3 billion light years away, we are seeing what it looked like 3
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This note was uploaded on 10/23/2011 for the course ENG 240 taught by Professor Unk during the Spring '11 term at Ocean County College.

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hw 1 astronomy - Jennifer Jacob Phys 180 September 9, 2011...

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