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hw4solution - Homework 4 1. p. 422 Questions for Review...

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Homework 4 1. p. 422 Questions for Review #2—Why do sunspots appear dark? Sunspots appear dark because they are cooler than the surrounding photosphere. The temperature of the photosphere is 5800 Kelvins, but in the darkest part of a sunspot, the umbra, the temperature is only 4500 Kelvins. By itself the spot would certainly be considered hot, but next the surrounding photosphere, it is 1300 Kelvins cooler. It is the contrasting temperatures between the two regions that makes the sunspot appear darker. 2. Explain why auroras are common in Alaska, but rare in Maryland. When a solar flare or a coronal mass ejection occurs in an active region on the Sun, a tremendous number of high energy solar particles are hurtled outward. Most of the particles are ions with an electrical charge, so their motion is affected by the Earth’s magnetic field. While most of these particles sweep past Earth, some are directed along the Earth’s magnetic field lines. The particles are directed into the polar regions (see Fig. 36.4 p. 272).
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This note was uploaded on 05/18/2008 for the course ASTR 101 taught by Professor Deming during the Spring '07 term at Maryland.

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hw4solution - Homework 4 1. p. 422 Questions for Review...

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