h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

The year 622 is the date of the Hegira, the flight of the prophet Mohammed from Mecca to Medina. This is the most important date in the history of Islam, and is used as the beginning of the Islamic Calendar, similar to 0 AD in the Christian Calendar. Note that the 622 year gap between Christian and Islamic calendars hasn't remained constant because the Islamic calendar is lunar, and each year is 354/355 days long. For example, a Morrocan banknote that I have to hand gives the year 1987 AD as 1407 AH.

Using Biblical evidence, Archbishop Ussher calculated that the beginning of the world occured in 4004 BC, on October 23rd - a Sunday.

By contrast, the Jewish calendar regards the year of creation as 3761 BC, and denotes this as 'AM' - Anno Mundi.

Some interesting 'coincidental' dates are as follows

1564: birthdate of Shakespeare and Marlowe
April 23rd 1616: death of Shakespeare and Cervantes.
1685: birthdate of Bach, Handel and Scarlatti
1865: birthdate of Dukas, Glazunov and Sibelius
1882 to 1941: the lives of James Joyce and Virginia Woolf.

There are lots of these - does anyone else have any good ones?

Your calendar ones are good - suggesting a lot of dates could be viewed and reviewed in different ways. I like the Great October Revolution in Russia which took place in November because they hadn't Gregorianised their calendar until after.

But as for coincidences:

My birthday is January 25th, just like Robert Burns the 18th-century Ayrshire farmer and Excise man. I was not born in the same year but nearly. I believe he's dead though, and I'm not feeling terribly well.

In the very same year that I was five, Sputnik was launched.

I'm not sure I quite understand what it is you are after with these dates but:

13.4.37 the Ark Royal was launched and last Tuesday I saw a bit of a rainbow. I'm not exactly sure of the last date but I can find out.