A saturday.
January 1st, 1977, was a Saturday.
Tuesday
January 1, 2012 will fall on a Sunday.
Wednesday
Wednesday
It was a Thursday.
January 1st 2004 was a Thursday.
January the 1st 2011 was on a Saturday.
January 1, 1988 fell on a Friday.
Tuesday 1st January 1985.
January 1st, 2200 will fall on a Wednesday.
Not always. For example: January 1st, 1962 was a Monday but January 1st of 2012 was a Sunday. For other part: January 1st, 1955 was a Saturday and January 1st, 2005 was a Saturday too. In general, your 50th birthday falls on the same day of the week of your birth or one day less.