Skyscript Astrology Forum

Potentially there is an interesting wrinkle to the problem of day of the week. In 1582 Pope Gregory erased about 10 days from the month of October. October 6th didn't exist (it became October 15th). I don't know if the days of the week skipped or not but my guess is that it probably went from something like a Saturday October 5th to a Sunday October 15th (or maybe Sunday October 5th to Monday October 15th) to fix the slide of precession on the Julian calendar for the previous 1000 years or so.

In the UK the dates didn't get fixed until around 1711 (not sure exactly when) but I remember reading that there were threats of riots over workers losing a weekend which suggests a re-ordering of the days of the week? Sorry I don't remember the source as this was at least a couple of decades since I saw it.

Zoidsoft wrote:

In the UK the dates didn't get fixed until around 1711 (not sure exactly when) but I remember reading that there were threats of riots over workers losing a weekend which suggests a re-ordering of the days of the week? Sorry I don't remember the source as this was at least a couple of decades since I saw it.

Hi Curtis,

I am losing heart a bit here. Seems like you have already forgotten the the reply I made to you on the traditional forum on the adoption of the Gregorian calendar across Europe a few weeks ago!

http://skyscript.co.uk/forums/viewtopic ... c&start=15

Bear in mind 'the colonies' like America followed the same calendar change date as the rest of the British Empire.

There were indeed calendar riots in England in 1752 to the cry of 'give us our eleven days!'

http://www.jstor.org/discover/10.2307/6 ... 2599891637

http://www.academia.edu/2342015/Give_us ... even_days_

It wasn't totally irrational if you were concerned about practical issues like rents, leases, or payment dates by your employer.

Plus imagine if your birthday was skipped during September 1752? The people effected would have been all Sun Virgo for heavens sake! They do notice these kind of details.

Mark

Ps You moved to New York!

Mark wrote:Hi Curtis,

I am losing heart a bit here. Seems like you have already forgotten the the reply I made to you on the traditional forum on the adoption of the Gregorian calendar across Europe a few weeks ago!

Ps You moved to New York!

Hi Mark,

I don't remember seeing it to begin with. It's been a hectic summer for me and sometimes I am away from this forum for a couple of weeks at a time. I moved back to my original home (my fathers farm in upstate NY which has been in the family since the civil war).

When the day begins is a historical and cultural convention.

In Judaism the day begins or ends just after sundown when 3 stars are visible in the sky. but getting times and even dates was a big problem in Antiquity, which is why observant Jews outside of Israel allow two days to celebrate each of the major holy days, with the idea that at least one of them will be correct.

In ancient Egypt, so far as I can make out, the day began at sunrise: when the sun first peeped over the horizon.

I don't know when midnight became a convention nor Greenwich mean time, but the history of time conventions is out there, probably in Wikipedia.

I didn't need to glance at a clock on the wall when my children were born: after being in unmedicated labour for hours, I was too pre-occupied during the delivery. But a nurse stood by with a stop-watch and my children's birth times were recorded in their birth certificate. Procedures vary by jurisdiction.

In the U. S. rounding up or down to the nearest 5 minutes seems very common. A century ago, times were often given only to the nearest hour.

Then you really have to look at war time, daylight savings time, &c; in a given jurisdiction, although most astro-programs account for this. In Canada, there still are a dozen or so communities that stay on standard time and I note that Astrodienst would be off by an hour in summer for them. Arizona is a piecework, with some Native Americans being on or off daylight savings and the the state as a whole sticking to standard time.

Ptolemy (Tetrabiblos) mentions the problems of accurately measuring birth times given the difficulties of recording time in his era. But in addition to their crude instruments, people also used the (geocentrically) rotating fixed stars and possibly moon phase as both clocks and calendars.

I found this interesting nugget on Wikipedia:

The astronomical day had begun at noon ever since Ptolemy chose to begin the days in his astronomical periods at noon. He chose noon because the transit of the Sun across the observer's meridian occurs at the same apparent time every day of the year, unlike sunrise or sunset, which vary by several hours. Midnight was not even considered because it could not be accurately determined using water clocks. Nevertheless, he double-dated most nighttime observations with both Egyptian days beginning at sunrise and Babylonian days beginning at sunset. This would seem to imply that his choice of noon was not, as is sometimes stated, made in order to allow all observations from a given night to be recorded with the same date. When this practice ended in 1925, it was decided to keep Julian days continuous with previous practice.

Regarding the Indian tradition different astronomers worked with both a midnight and sunrise timing.

From Wikipedia:

In the Arya-siddhanta, a lot work on astronomical computations, is known through the writings of Aryabhata's contemporary, Varahamihira, and later mathematicians and commentators, including Brahmagupta and Bhaskara I. This work appears to be based on the older Surya Siddhanta and uses the midnight-day reckoning, as opposed to sunrise in Aryabhatiya. It also contained a description of several astronomical instruments: the gnomon (shanku-yantra), a shadow instrument (chhAyA-yantra), possibly angle-measuring devices, semicircular and circular (dhanur-yantra / chakra-yantra), a cylindrical stick yasti-yantra, an umbrella-shaped device called the chhatra-yantra, and water clocks of at least two types, bow-shaped and cylindrical.

So we have traditions starting the day from sunrise, noon, sunset and midnight.

Regarding Greenwich Mean Time (GMT)

Wikipedia to the rescue again!

Ambiguity in the definition of GMT
Historically GMT has been used with two different conventions for numbering hours. The long-standing astronomical convention dating from the work of Ptolemy, was to refer to noon as zero hours (see Julian day). This contrasted with the civil convention of referring to midnight as zero hours dating from the Romans. The latter convention was adopted on and after 1 January 1925 for astronomical purposes, resulting in a discontinuity of 12 hours, or half a day earlier. The instant that was designated December 31, 5 GMT in 1924 almanacs became January 1, 0 GMT in 1925 almanacs. The term Greenwich Mean Astronomical Time (GMAT) was introduced to unambiguously refer to the previous noon-based astronomical convention for GMT. The more specific terms UT and UTC do not share this ambiguity, always referring to midnight as zero hours.

Interesting that the Roman civil convention was to use midnight as we do today. In Europe at least then the idea of calculating the civil calendar new day from midnight dates back to the Roman Empire and Byzantium.

Can we therefore assume this cultural convention continued on to influence medieval and renaissance European thinking and subsequent settlement in the Americas?

The International Meridian Conference held in Washington DC in October 1884 adopted Greenwich as the prime meridian. It also established midnight i.e. 12 midnight as the start of the civil day i.e. 0:00 hours, the astronomical day used midday i.e. 12 noon as the start of the day - a practice that continued until January 1, 1925.

The Islamic approach seems to be based on calculation from the dawn.
This is different from the use of the new moon at sunset for the start of the new Islamic lunar month. The commencement of a new day and commencement of a new month are different issues.

This site sets out an Islamic view:

http://muslimvilla.smfforfree.com/index ... pic=2937.0

By the recurrent use of the term 'dawn' I assume this means twilight rather than sunrise although I am not clear how this can be accurately timed. This probably wasn't a practical concern when this tradition was established since its main purpose was to identify the first of the daily prayers in Islam. The Fajr prayer (Arabic: ???? ?????? ?al?t al-fa?r, "dawn prayer") is the first of the five daily prayers offered by practising Muslims.

The ancient Zorasteran faith also considers sunrise as the start of the day:

http://zoroastrianheritage.blogspot.co. ... start.html

I dont think this issue is just one of academic historical interest. It is a necessary consideration for any astrological researcher examining birth dates for older or ancient charts to be conversant with the prevalent attitude towards the calculation of the day commencement. Especially, when we have no time recorded!

Mark

A Historical View of the Hindu Astronomy: From the Earliest Dawn of Science ...
By John Bentley

There is a spurious Arya siddhanta floating around too.

http://books.google.co.in/books?id=YcNX ... navlinks_s

search for spurious Arya siddhanta

PD

I was recently reading Ptolemy, and he had quite the interesting discussion regarding when a new year began. He discussed how a case could be made for the year beginning at each of the four cardinal points of the year...the equinoxes and the solstices. He also discussed that each of these cardinal points *is* a new beginning in a sense.

Anyways, while reading this, I noticed something. It seems that there is a strong correlation in cultures in the beginnings of the day and of the year. It seems natural that midnight would correspond to the Winter Solstice, dawn to the Spring Equinox, noon to the Summer Solstice, and sunset to the Fall Equinox.

Anyways, a few correlations I have noticed are the astrological year and day. Of course, the astrological year begins at 0 Aries, the Spring Equinox, and the day begins at sunrise. In the modern civic system the day begins at midnight and the year begins close to the Winter Solstice. In Judaism, the day begins at sunset and the year in the Fall. I am not sure if this is always the case, but there seems to be a VERY strong correspondence.

I don't know if this really matters to anything, I just thought it was a rather interesting bit of trivia.

Very interesting Myriam.

There is also a climatic explanation.

In the case of Judaism, the beginning of the year in Autumn probably relates to the start of the rainy season in Israel (and in the Mediterranean region, more generally) which was so crucial to their harvest. It was preceded by a long period of introspection and asking for forgiveness: the OT idea that God would punish the sinners by withholding rainfall. In Egypt we would look at the swelling of the Nile. I don't know that the geocentric astronomy came first, although the fixed stars and moon did serve as the original paperless calander.

May Day was a bigger spring holiday in northern Europe than Easter (the spring equinox,) as March is still pretty wintery in northern climes.

Interestingly in Judaism, the rule (today anyhow) is 3 stars also have to be visible, as well as sundown, for the start of the new day. Probably the rabbinical idea of taking The Law and setting up a fence around it to minimize transgressing it accidentally. Sundown and stars are easily observed, unlike midnight. For cloudy nights, you need a time-table.