February 11, 2013

Introduction to Astronomy

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After completing a Scala course on Coursera in November, I was ready to try another. Since I have an interest in astronomy I signed up for the Duke University Introduction to Astronomy course. After eight weeks of lectures and assignments it has just finished.

Whenever there is an astronomy documentary on TV, I usually tune in for at least the first few minutes. Normally I turn them off fairly quickly as most are aimed too low or just go too slow. The last one I watched contained about 15 minutes worth of information in it’s 60 minutes run time. There was no similar problem with this course. While it started gently with positional astronomy and Newtonian physics, it quickly moved on with a week each on planets, stars, stellar evolution, relativity, galaxies and cosmology.

While many of the facts in the roughly 3-4 hours of lectures per week were not new to me, the course also covered how those facts are mathematically determined. Thus while a documentary my say something like “after 10 billion years the Sun will start to expand”, this course goes further. It presents the maths to calculate the amount of energy released by nuclear reactions in a star’s core; how quickly the fuel for these reactions is exhausted and how the pressure inside the star changes at this point (including quantum effects like electron degeneracy pressure). The maths stops just short of calculus (thus many formulas are presented without derivation), so high school level is adequate to understand everything presented.

There was an assignment every week requiring usage of the maths presented to solve various problems. This is where the course let itself down. The first assignment was hard, had a one week deadline and did not inform the student where they were going wrong. After close to 16 hours of effort I submitted on time and as the deadline passed received my grade of 95%. Although I was quite proud, I did not have the time to continue with the course if the future assignments continued in the same fashion. The hours were not reasonable, especially for a course that advised spending 6-8 total hours/week. However, it seemed that many other people complained, so all further assignments had a 3 week deadline, allowed multiple submissions and gave instant feedback. Still assignments normally took me around 6 hours – so the course was an unexpected time sink. Furthermore, the lectures and marking scheme often contained mistakes that impacted assignment questions. It is extremely frustrating to try solving a problem, getting feedback that it is wrong and spending time trying to work out the error when it is in fact a mistake caused by the lecturer! I soon learned to wait and only start assignments after they had been available a week (by which time the errors had been spotted and fixed).

A very interesting and informative class – unfortunately marred by assignment errors and required more time than expected.


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