Calculating the Sun's Angular Velocity -- Example



Tracking the movement of a sunspot helps us determine the Sun's rate of rotation.



 This is the template


Look at your sun sketches and pick a sunspot group which is easy to see
and which appears over a period of several days.
Make a transparent copy of the template, lay it over your images,
and figure out how many degrees your spot group has moved.
Like this:







[Amara -- We need 2 images of a sunspot group, with the grid superimposed on them. 
Beneath each we need a time-stamp.  Can you create these???]




So, the spot group has moved 90 (whatever) degrees in 7.5 days.
To compute the Sun's rotation period:





The Sun's Angular velocity = degrees the spot has covered / time it took for the spot to travel



angular velocity = 90 / 7.5  = 12 degrees/day



Sun's rotation period = 360 degrees / angular velocity








So, in this example, we find the Sun's rotation period = 360/12 = 30 days








 Return to the Angular Velocity exercize