Tibaldo and the Hole in the Calendar

18 Oct

“Tibaldo and the Hole in the Calendar” is a great book.

It’s a historical fiction book about the change over from the Julian calendar to the Gregorian calendar.

Do you know much about the calendars?

I didn’t, which is why I decided to hunt down a copy of the book

and read it to my boys.

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Did you know that we lost 10 days in the change over?l

Well the Catholic countries did.

They changed over in 1582.

Many protestant countries thought the Pope was up to mischief

so they waited until 1752 and they lost 11 days.

And Eastern Europe waited until various years during World War 1.

Yep, that late.

So why did we need to make the change?

Well the Julian calendar was created on the basis of a year being 365 days and a quarter, exactly,

(which is why leap years used to occur every four years)

However, it turns out that a year was actually a smidge shorter than their calculations.

This meant that our man-made calendar was creeping ahead of the actual solar year.

and that really messed with the Church’s calculations of special days,

particularly Easter.

So they had to pull the calendar back into line.

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Oh, and if you are wondering about leap years,

they don’t happen every four years anymore.

Every hundred years we miss a leap day.

So on 2100 and 2200 and 2300 we won’t have a leap day.

However, every four hundred years we get to keep the leap day,

which is why the year 2000 was a leap year,

as will be 2400.

This dabbling with the leap year

helps keep the new calendar mostly in sync with the solar year.

(It’s actually still out a smidge but we won’t creep ahead a whole day for hundreds of year).

Oh, we thoroughly enjoyed “Tibaldo and the Hole in the Calendar”

It was a fascinating read.



Posted by on October 18, 2016 in History, Mathematics, My Library


3 responses to “Tibaldo and the Hole in the Calendar

  1. Lisa

    October 18, 2016 at 10:02 pm

    Tracey, that books sounds fascinating. What age groups would you say it would be for (primary/tweens/teens)? Many thanks

    • Tracey

      October 18, 2016 at 11:58 pm

      Probably tweens. But it would be fine for any of them. It has a lot of other history and science in it as well. The main character is studying to be a physician so there’s talk about medicine and practitioners in that century. There’s also talk about families, schools, the papal states, midwifery, Latin, and astronomy. It’s a very cleverly written book.

      • Lisa

        October 19, 2016 at 8:41 am

        Thanks Tracy, appreciate that advice.


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