77
votes
Accepted
Why does the amount of days in an year on average of the Gregorian calendar only have 4 decimal places (365.2425)?
Why? Because there was no point.
First, according to more modern astronomical measurements, the current length of the year is closer to about 365.2422 days, so they would've been relatively less ...
- 8,276
25
votes
What is the reason that not all roman emperors named a month after them?
Suetonius has this to report about Tiberius, the second emperor and the third Caesar:
[H]e at first played a most unassuming part, almost humbler than
that of a private citizen. Of many high ...
- 25.7k
21
votes
Accepted
Was Mid-Night always considered the transition point between two days in Gregorian/Julian Calendars?
It wasn't simple to track time at night until the invention of mechanical clocks. Before that the breakpoint between days was sunrise (early Roman), solar midnight (later Roman), or sunset (Athenians, ...
- 23.2k
20
votes
Why does the amount of days in an year on average of the Gregorian calendar only have 4 decimal places (365.2425)?
The Gregorian Calendar was introduced (to the Catholic World) in 1582, the result of preparation over the preceding five or so years.
However the popularization of decimal fractions would wait another ...
- 72.3k
19
votes
Accepted
Why is the leap day on February 29th?
The ancient Romans used to have the new year at the end of February. To fit the lunar and solar calendars, an extra month was sometimes added after February. This practice continued even after the ...
- 5,671
15
votes
When did Europeans make Sunday rather than Saturday the seventh day?
In the 1970s the day numbering was standardized worldwide, culminating in an UN decision. The current version of the standard is ISO 8601. Some countries were more timely than others in adopting this ...
- 16.8k
15
votes
Accepted
Why was the date moved by 10 days instead of 9 during Gregorian calendar reform?
The date was moved by ten days because that's how many days the Julian calendar was off by.
You may have thought the time skip was meant to compensate for the drift of nine days between 325 and 1582. ...
- 97.4k
14
votes
What is the reason that not all roman emperors named a month after them?
Actually several did:
Caligula renamed September to Germanicus (Suetonius, Caligula, 15) in memory of his father.
Nero renamed April to Neronium (Suetonius, Nero, 55).
- 4,308
13
votes
Accepted
Why have both July and August 31 days?
First, the answer to your second question.
[W]ho invented that calender?
The current calendar that most of the western world uses is Gregorian Calendar1, which is an improvement over Julian ...
- 3,073
12
votes
Has there ever been a month with 32 days?
Not that I know of, but in 1712 in Sweden, February had 30 days.
Sweden, being a Protestant country, was initially suspicious of the "papist" Gregorian calendar, but decided to adopt it in the early ...
- 5,671
12
votes
Does it make sense to mention months (and days) in any BCE date?
Not a historian, but yes it makes sense. Months are associated with certain seasons and astronomic phenomena (equinoxes, solstices) and months with days can help with orientation if several events ...
- 8,383
11
votes
Accepted
When was the change from kalends, ides and nones to numbers
This is covered by Bonnie Blackburn and LeoFranc Holford-Strevens in their book The Oxford Companion to the Year: An exploration of calendar customs and time-reckoning (1999, reprinted with ...
- 316
11
votes
Accepted
When did Europeans make Sunday rather than Saturday the seventh day?
Sunday is the first day of the week and Saturday is the seventh. That conforms to a tradition that goes back at least to ancient Jews long before Christianity.
It should be noted that other ways of ...
- 13.4k
10
votes
Which calendar to use in English for non-European countries?
A modern secondary historical paper or book should always use the Gregorian Calendar and the era of Exiguus. For pre-Gregory dates the proleptic calendar should be used. The reason for this is so that ...
- 37.8k
10
votes
Which months were added during the Roman Empire?
The original Roman calendar is believed to have been a lunar calendar, which may have been based on one of the Greek lunar calendars. As the time between new moons averages 29.5 days, its months were ...
- 1,258
10
votes
How did ancient cultures identify a new moon when it can never be seen?
In Jewish custom, all calendar questions were decided by the court (Synedrion).
It was a duty of everyone who spotted the new Moon to report to this court as soon as possible.
But of course, the new ...
- 38.5k
10
votes
Accepted
Has there ever been a month with 32 days?
It seems the Julian calendar had a month with 32 days on leap years at one point:
An inscription has been discovered which orders a new calendar to
be used in Asia to replace the previous Greek ...
- 23.2k
10
votes
Accepted
Has anyone created a binary calendar?
The core issue is that the purpose of a calendar is to track astronomical events, and in particular, their relations. The three that are universally tracked are the three that are obvious to anyone:
...
- 8,276
10
votes
Accepted
What was the calendar used by ancient Palmyrenes?
The year 311 BC is the anchor for the beginning of the Seleucid era:
The Seleucid era ("SE") or Anno Graecorum (literally "year of the Greeks" or "Greek year"), ...
- 80.8k
9
votes
What, if any, celebrations or commemorations were done in 1000 AD?
Most people in Christian medieval Europe who gave the matter any thought seem to have expected that the end of the first millennium would also be accompanied by the end of the world. However, it is ...
- 77.3k
9
votes
What calendars were used in Eastern Rome?
Many different local calendars were used in the eastern and western parts of the Roman empire. The Julian calendar introduced about 44 BC was the official calendar of the Roman republic and empire ...
- 19.1k
9
votes
When did the current 7-day week cycle begin?
Timothy is somewhat correct with identifying Babylon, however the Babylonians only borrowed the system. Most of our time keeping dates all the way back to ancient Sumeria (2600BC-ish?) and is ...
- 2,722
9
votes
Was the date skip of the Gregorian calender reform understood to skip weekdays accordingly?
The change over to the Gregorian Calendar happened over a period of over 300 years across the western world. Consequently the number of skipped days varied by country depending on when they changed ...
- 19.3k
9
votes
Has there ever been a month with 32 days?
Of course it depends whose months you look at. Part of the decimalization project in revolutionary France was Claude Boniface Collignon's proposals for decimalizing time. He called for ten "solar ...
- 27.6k
9
votes
Accepted
When did humans start numbering years?
When did humans start to keep track of years with unique identifiers for each year? [...]
My questions is: when was that "later point"? When did we start "numbering" the years to ...
- 23.2k
9
votes
Accepted
Has a region/territory/country using the Western 7-day week ever got 'out-of-sync' for the day of the week?
As per the link posted by Brian Z ("One Time Fits All" by Ian R. Bartky), the Pitcairn Islands could have been this at some point between 1790 and 1808; during this period they "lost ...
- 206
8
votes
In Russia, are the anniversaries of the various events that occurred in 1917 and '18 observed according to the Old Style or the New Style calendar?
None of the events are celebrated in Russia nowadays. In Soviet times, only the day of the October Revolution was celebrated, on the 7th November, which is according to the New-Style calendar. In ...
- 219
8
votes
Accepted
How are Julian and Gregorian dates usually represented in historical works?
There are two distinct calendar issues involved here:
Different calendars - eg in 1640, the Julian calendar was used in England and the Gregorian in France, so that 28 January in England was 8 ...
- 9,112
8
votes
What date format was used at Pompeii around the Mt Vesuvius eruption
For such at mighty and well-organised empire, ancient Rome actually had a remarkably bad system for identifying a given year. Multiple methods were used, but the most widely used format seems to have ...
- 2,073
7
votes
In Russia, are the anniversaries of the various events that occurred in 1917 and '18 observed according to the Old Style or the New Style calendar?
According to the new style. Even though the Revolution is called "October Revolution", it is celebrated in November, which may be confusing to some.
The date of the Tsar's abdication is not ...
- 32.5k
Only top scored, non community-wiki answers of a minimum length are eligible