I thought this may be posted. A short animation shows  the brightness 
of the rings. First one was taken on March 18th, 2009 (shortly  after 
opposition) and the second one was taken on May 20th, 2009. This is due to  the 
opposition effect. Also, see the different intensity of the rings' shadow on  
the globe and with a slight tilting.

[Frank J Melillo  Holtsville NY U.S.A]