Light Answers - Answers to Homework #1-Light Basic...

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Answers to Homework #1---Light Basic Observations- 1) The major difference between astronomy and other sciences is that with astronomy there are no controlled experiments; you must rely upon the Universe without being able to tweak things, or do things again. What is remarkable is that despite that limitation, we can find out so much about the Universe. For example, even though stars evolve over billions of years, we don’t have to wait that long to find out what happens; although we can’t see a single star evolve, we can piece together what is happening using many stars in different stages of evolution. 2) Other spectral regimes are important because some processes produce radiation that is not in the visible; for example, some stars that are almost completely invisible in the optical wavelengths produce tremendous quantities of x-rays. (Neutron stars, for example). Thus, we can piece together many different ideas by using different wavelengths. 3) X-rays do not penetrate the Earth’s atmosphere, so we need to send up satellites to perform these observations. Modeling Task 1 Two possible explanations are: a) the Sun goes around the Earth and b) the Earth goes around the Sun. (It actually took thousands of years for us to figure this one out!). On the basis of daily observation of just the Earth and Sun, there is no way to rule out one or the other. It took Copernicus’ and Kepler’s observations of the other planets to show that it was highly unlikely that the Sun went around the Earth. Note that Ptolemy tried to jig things up with his Earth centered scheme to explain these retrograde planetary motions, so this is by no means an obvious thing! Questions:
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This note was uploaded on 04/02/2008 for the course PHYSICS 750 taught by Professor Matilisky during the Spring '08 term at Rutgers.

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Light Answers - Answers to Homework #1-Light Basic...

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