Observations of the sun through the months of April and May 1998.
(images of the sun provided courtesy of Learmonth, Australia and Holloman AFB, NewMexico)
http://www.sel.bldrdoc.gov/current_images.html
It is easy to see evidence of solar differential rotation when solar features are followed on a daily basis. Beginning on 98/04/13  observe the elongated  region of sunspots on the lower southern hemisphere.  The effect that differential rotation has on its shape is evident as the faster motion of the equatorial plasma pulls on the northern half of the sunspot group and pulls it around so that by 98/04/20 the entire group is leaning in the opposite direction.  A comparison of  the positions of bright region on the sun's equator and the dark area on the southern hemisphere between 98/04/01 and 98/04/05 show the relative speeds of the equator and the poles.