August 9th, 1979 fell on a Thursday.
The 9th of August can occur on any day of the week. As the question was asked in July 2014, it is possible you were referring to August of 2014, in which case the answer is Saturday.
9th February 1979 was a Friday.
January 9 1979 was a Tuesday.
August 20 1979 was a Monday.
August 4th, 1979 was a Saturday.
August 2, 1979 was a Thursday.
its on a Monday!
Tuesday
It was a Monday.
Tuesday
Thursday