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Posts Tagged ‘New Year’

In the last week I have been putting together the final edits for the book that I have been writing with Brian Clegg – Ten Physicists who transformed our understanding of reality, which will be published later this year. One of the issues which we needed to clarify in this editing process were the dates of Newton’s birth and death. The reason this is an issue is that the calendar system was changed in the period between the 1500s and 1700s, which spans the years that Newton was alive. In 1582 the Gregorian calendar was introduced by Pope Gregory XIII, because the Julian calendar’s system of having a leap year every four years is not exactly correct (I will blog separately about the details of why having a leap year every four years is not correct).

'Ten Physicists who transformed our understanding of reality" will be out December

‘Ten Physicists who transformed our understanding of reality” will be out December


Different countries adopted the Gregorian calendar at different times, with Catholic countries adopting it before Protestant ones. Newton was born in England in the mid-1600s, and when he was born England was still using the Julian calendar. Under the Julian calendar, he was born in the early hours of the 25th of December 1642. But, by that time, many European countries were using the Gregorian calendar, and so had someone in e.g. France heard of his birth on that day (imagine radio existed!), their calendar would have said that the date was the 4th of January! But, which year, 1642 or 1643? This is where another subtlety of calendars arrises, because starting the year on the 1st of January is something else that changed during this period.

In England, the year traditionally began on the 25th of March, and so the 4th of January (the one 10 days after the 25th of December) was still in 1642! The 4th of January 1642 actually came after the 25th of December 1642, because the year did not change to 1643 until the 25th of March! (The year starting on the 25th of March is also why the financial year (Tax year) in Britain still starts on the 6th of April, the date to which that the 25th of March was adjusted when the Gregorian calendar was finally adopted in Britain.)

However, in France (for example) they switched to starting their year on the 1st of January in 1564 (prior to this France started their year at Easter), so again this hypothetical person in France who heard of Newton’s birth would have said the date was the 4th of January 1643 (for more about this see here).

The first page of the Papal bull announcing the introduction of the Gregorian calendar, which was published on the 24th of February 1582

The first page of the Papal bull announcing the introduction of the Gregorian calendar, which was published on the 24th of February 1582


A similar confusion arises over Newton’s death. Under the Julian calendar, he died on the 20th of March 1726. At the time of his death, England was still using the Julian calendar, and was also still starting its year on the 25th of March (it switched to the Gregorian calendar and to starting its year on the 1st of January in 1752). So, had Newton died just 5 days later his date of death would have been the 25th of March 1727, which to any casual reader would imply he was a year older than he actually was. To someone in France, the date of Newton’s death would have been the 30th of March 1727.

Confused? 😉

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Today (23rd of January 2012) is Chinese New Year, so happy Chinese New Year to all my Chinese friends and students. Today, over 1 billion Chinese will be celebrating the start of the year of the Dragon (龍). From what I heard yesterday on the radio, many Chinese couples await to have children in the year of the Dragon, as this year is thought to be the most lucky of the cycle of 12 animals.

Chinese New Year

Candles being lit for Chinese New Year

Last year (2011), Chinese New Year was on the 3rd of February, and next year (2013) it will be on the 10th of February. The table below shows the dates of Chinese New Year from 2009 to 2014.

year date
2009 26th January
2010 14th February
2011 3rd February
2012 23rd January
2013 10th February
2014 31st January

Clearly, Chinese New Year does not fall each year on the same date in the civil calendar. So, how is it calculated?

The Chinese calendar is an example of a lunisolar calendar, which means it depends on both the Moon (Luna) and the Sun (Solar). The same is true of the traditional Jewish calendar, and the calendars of many other civilisations and religions including Hindu, Tibetan and Buddhist calendars.

The date of the Chinese New Year is determined by the following, very simple, formula.

The date of the Chinese New Year is the day of the 2nd New Moon after the Winter Solstice (the shortest day of the year in the Northern Hemisphere).

This fixes it between the 21st of January (the earliest it can be, which would occur if there were a New Moon on the day after the Winter Solstice), and the 20th of February, which would occur if there were a New Moon on the day of the Winter Solstice.

So, it is that simple. Today (23rd of January) is a New Moon, and the previous New Moon (the first after the Winter Solstice) was on the 24th of December, with the Winter Solstice itself falling on 22nd of December in 2011. Next year, 2013, the first New Moon after the Winter Solstice will be on the 11th of January, the 2nd one will be on the 10th of February, so this will be the date of the Chinese New Year in 2013.

How will you be celebrating Chinese New Year?

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Last night was Halloween, and in many countries across the World children went out “trick or treating“. We had our share of visitors at our door, dressed in various costumes asking for sweets.

What a lot of people don’t realise is that Halloween was, originally, a Celtic festival. November the 1st marked the start of the winter to the Celts, and was the start of their year. In Welsh, the term for Halloween is “Nos Galan Gaeaf“, which literally means “the eve of the first day of Winter”, with “Calan Gaeaf” being the 1st November.

The modern day practice of “trick or treating” has its origins in old customs which existed in the Celtic parts of the British Isles as far back as the late 1800s. But the modern form is very much an American invention, where it apparently became popular in the 1950s.

In fact, when I moved to the USA in 1992 it was one of the major events of the “fall season“, along with Thanksgiving. When I had my own children (all of whom were born in the USA), I would take them “trick or treating“, typically on the Sunday before Halloween so that they could do it in daylight.

Modern day trick or treating in the USA

When I moved back to the Disunited Kingdom in 2001 trick or treating had infiltrated into Wales, whereas it did not really exist back in 1992 when I had left. Over the last 10 years the level of fuss made about Halloween has certainly increased, so that now it seems to me the level of costume wearing and trick or treating which goes on here is almost on a par as the US.

I find it quite amusing that what was originally a Celtic festival to mark the passing from the old year to the new one has been taken by the United States, repackaged and “sold back” to the countries from where it originated in a new, and possibly more popular, guise.

So is the way of the World…

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