Simplify the following text for a Grade 4 native English-speaking person.
Original: From its launch in 1999 , SmackDown broadcast on Thursday nights , but as of September 9 , 2005 , the show moved to Friday nights .
Simplified: From its launch in 1999 , SmackDown ! was shown on Thursday nights , but as of September 9 2005 , the show moved to Friday nights .