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Homework Help: How do I measure the synodic rotation period using sunspots?

  1. Dec 3, 2013 #1
    Ok so I have a project and I have to measure the sidereal synodic rotation period of the sun using sun spots. I have included a diagram of what to do. but I will explain it too. you take 5 images with a common sunspot and track it's movement on those 5 days (on the diagram, the sunspot is labeled s1 - s5, where s = sunspot and # = the day it was observed)

    you draw a line connecting the sunspots and it should be parallel to a line across the center of the sun. then you draw a semicircle across the line connecting the sunspots and transfer the sunspots onto the semicircle, this is the actual position of the sunspots on the sun.

    I have done all this, but here is where I am confused, it says you have to measure the angle between each pair, not all the pairs, but only for at least 8 pairs. how would i get 8 pairs from 5 sunspots? does that mean angle b/w s1 and s2 = 1 pair and angle b/w s1 and s5 = 2nd pair etc...and I need to do this for 8 pairs?

    I do have the time and date of when the sunspots were observed, which I didn't show on the diagram or here, but how would I use the information of the angle and the time to compute the synodic period of rotation? is there a formula i have to use which incorporates angles and time? because so far I have came across 3 formulas:

    1) the regular 1/s = 1/sidereal - 1/earth's sidereal...I can't use this because I don't know the sidereal period, thats what I have to find at the end.

    2) synodic rotation period = circumference of sun/speed of sunspot travel...I don't think I am suppose to use this because it doesn't ask me to calculate the speed or use the circumference anywhere

    3) synodic period = 360/slope...is this the one to be used? I am not sure about this.

    The link to the diagram is given below, any help would be appreciated


  2. jcsd
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