Possible Clues:

• They need a lot of space for their arrival and departure
• These outsiders arrive at the backstreet
• Bill Haley and His ___
• Name on the 2012 Rock Hall of Fame induction list
• "Rock Around the Clock" backups
• Noted 1950s backup band
• Tailed streakers
• 'Dirty snowballs,' to some astronomers
• Space streakers
• Extraterrestrial bodies