user: Question: What was the original air-date that had 4.77 million viewers?
Columns: ['Episode #', 'Title', 'Directed by', 'Written by', 'Originalairdate', 'Viewers (millions)']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, '"Second Life"', 'Brendan Maher', 'Ed Whitmore', '5 July 2010', '6.37']
SQL:

assistant: SELECT "Originalairdate" FROM "Table" WHERE "Viewers (millions)" = '4.77';