Conversation so far:
What was happening in 1977?
Rick Savage, Tony Kenning, and Pete Willis, all students at Tapton School in Sheffield, South Yorkshire, formed a band called Atomic Mass in 1977.
Did this turn into Def Leppard?
The band adopted a name proposed by Elliott, "Deaf Leopard.

Question: Why did they do this?
Self-contained rewrite: Why did Rick Savage, Tony Kenning, and Pete Willis rename the band Atomic Mass to Def Leppard?