Saturday.
February 12, 1979 was a Monday.
12 January 1979 was a Friday.
January 12, 1979, was a Friday.
December 12 1979 was on a Wednesday.
June 12, 1979 fell on a Tuesday.
Monday
Thursday
By googling it and finding which day of the week it was
Thursday was the day of the week of May 12, 1983
January 12, 1979 was a Friday.
12 May 1961 was a Friday.
12 May 1898 was a Thursday.