Tag Archive | Gregorian Calendar

When Easter Sunday Has Fallen On ‘April 1’, “April Fool’s Day” — Last Time Was 1956.

by Anura Guruge


Click to ENLARGE.


The sea change Gregorian calendar was introduced in October 1582.

Easter Sunday fell on April 1 two years later in 1584 — which, coincidentally, was also around the time the notion of “April Fool’s” kicked-in. One theory is that around this time, in France, the start of the New Year was moved from ‘April 1’ to ‘January 1’. Those who got confused by this move were referred to as April Fool’s. That, however, is one theory.

I have as yet not been able to work out why we get a 62-year gap … as between 1956 and 2018 and twice in prior years. The 68-year confounds me even further.

11-year gaps for such ‘movable holidays’ is common — the 11 having to do with the 7-day week and leap years every 4-years. As you can see we do get 11-year gaps quite often, just not the last time around. 35-year gaps are fairly common too.

But, 62- and 68-year are the LONGEST possible gaps for Easter.


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by Anura Guruge

RED LETTER DAY IN WORLD HISTORY. The Gregorian Calendar First Used, This Day, 435-Years Ago.

by Anura Guruge


Click to ENLARGE and study here. Wikipedia: en.wikipedia.org/wiki/Adoption_of_the_Gregorian_calendar


Pope Gregory XIII papal bull ‘Inter gravissimas’ in its original Latin form.


English translation of the key paragraph from Inter gravissimas. From: myweb.ecu.edu


Pretty significant day. The Papal States, France, Poland and Spain adopted the revolutionary Gregorian calendar on Thursday, October 4, 1582 — the NEXT DAY then having become Friday, October 15, 1582. Pretty incredible. 10-days were just expunged. Gone. Poof. If your birthday fell between October 5 to October 14, you were out of luck in 1582. Your birthday vanished.

In reality the adoption of the calendar did not cause much of a stir. Much of the European population, at the time, were not that concerned about daily calendars. They went by the seasons and each day as it unfolded.

But, this was a BIG day. It demarcated history’s very timeline!


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by Anura Guruge

The Divine Johann Sebastian Bach Was Born This Day 332-Years Ago; March 21, 1685!

by Anura Guruge




Click to ENLARGE and read snippet here. Wikipedia link: en.wikipedia.org/wiki/Johann_Sebastian_Bach


Kind of funny. ‘March 21’ is his birthday per the ‘Old System’ – i.e., the pre-Gregorian calendar. But, it would appear that in his time this would definitely would have been his birthday.

So, let’s tip our hat to this great composer.



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by Anura Guruge

Edmond Halley, Of Comet Fame, But Really A Brilliant, British Polymath Died 275 Years Ago — Today.

by Anura Guruge


Click to access the Wikipedia entry for “Edmond Halley”.


Edmond Halley (29 October 1656 to 14 January 1741 (new Gregorian calendar)), though best known for COMPUTING the periodic orbit of the comet that bears his name, was quite the man.

Son of a wealthy soap-maker in London, Edmond had the privilege of being able to pursue the many things that interested him.

Just a few of his many amazing achievements include:

  • Financing and publishing Sir Isaac Newton’s, quite literally earth-moving, Philosophiæ Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy) — which among other things included his eponymous laws of motion.
  • Worked out how to determine the size of the Solar System by observing transits of Mercury and Venus across the face of the Sun.
  • Reliably catalogued the stars in the Southern Hemisphere.
    ….
  • Built a working diving bell!
    ….
  • Realized that some comets were periodic and calculated the orbital period of one, 1P/Halley — which he never got to see!
    ….
  • Britain’s second Astronomer Royal.

He was an exceptional mathematician. He also made some major contributions in the fields of meteorology, geophysics and physics,


halleys_comet_-_may_29_1910

Halley’s famous comet; 1P. In 1910. Click to ENLARGE.

Last time around was in 1986 when it didn’t put on a big show because the Sun was between the comet and Earth when it was at its closest to Earth.

Next time — 2061! 45 years hence. I will not be around.

Google Doodle for Edmond Halley's 355th Birthday, November 8, 2011 (old calendar).

Google Doodle for Edmond Halley’s 355th Birthday, November 8, 2011 (old calendar).


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by Anura Guruge

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