Simplify the following text for a Grade 8 native English-speaking person.
Original: The solemn mass of beatification of don Jerzy PopieÅ uszko has been celebrated in Warsaw Sunday 6th of June 2010 , in the square that has a title of the marshal PiÅ sudski .
Simplified: On December 19 , 2009 , it was announced that Pope Benedict XVI had approved the decree of beatification of Father PopieÅ uszko . He was beatified on June 6 , 2010 in Warsaw 's PiÅ sudski Square .