Science
fiction conventions have been having masquerade balls for decades. Originally
costume party, where people dressed up in SF costumes and went to a dance,
the Masquerade gradually became a staged, competitive production as the
costumes became more elaborate. The skill shown by these costumes are truly
awesome, particularly since for most of the people involved it's only a
hobby, if sometimes an all consuming one.
Many large cities have a local
science fiction convention. Worldcon
is the largest and sometimes international SF con, the members of which
vote for the Hugo awards.