Monday
February 29th, 1985 was actually a leap year. So, this day of the week did not occur.
A week is larger than a day because a day has 24 hours but a week has 168.
A week is 7 days long, there is no 8th day in a week.
A day is one seventh of a week.
The Challenger Accident occured on Tuesday, January 28th, 1986.
The shuttle challenger, disintegrated after launch, killing all seven astronauts on board on Tuesday, January, 28, 1986.
The space shuttle Challenger exploded on January 28, 1986, which was a Tuesday.
September 11th can be on any day of the week
On Sabbaths and Jewish holidays. (The holidays can occur on any day of the week.)
Tuesday- D-Day occurred on a Tuesday.
The time of day or day of week does not seem to matter.
Thursday
Tuesday
Saturday.
It was a Thursday.
Monday