lpetrich
Contributor
Just saw the dropping of the ball in Times Square. I didn't give a good view of it, however, in the online broadcast that I was watching.
But what's in a day? A year?
First, when to begin a day. Sunrise? Noon? Sunset? Midnight?
All four conventions have been used by some people or other, though it's mostly astronomers who have used noon. They switched to midnight in 1925, to be like everybody else.
Whatever the convention, people at different longitudes will have days starting at different times relative to each other. A way out of that conundrum is to define a "prime meridian" as a longitude reference. Nearly 2000 years ago, Claudius Ptolemy defined one of the first, using the "Fortunate Isles" (The Canary Islands? The Cape Verde Islands?). Early-modern mariners and cartographers used several prime meridians before settling on the Greenwich one in the 1884 International Meridian Conference.
As to when to begin a year, here also, there are lots of conventions, scattered over the year. The Jewish year and the French Republican year begin around the autumnal equinox, the ancient Roman year originally began around the vernal equinox, our year begins a little after the winter solstice, the traditional Chinese year begins halfway between the winter solstice and the vernal equinox, etc. All northern-hemisphere seasons, I may add.
For counting the years, the first system used was the year-reign system. A modern version would go
As with longitudes, it is convenient to define some reference year that years are to be counted relative to. Several of them have been used, with ours being a calculation of when Jesus Christ was born.
The Jewish calendar has 5779, using a calculation of when the Universe was created according to the Bible. Archbishop James Ussher's calculation would give us 6023, and other calculations give us other year numbers. For the Masoretic version of the Old Testament / Tanakh / Hebrew Bible, it's usually around 6000, and for the Septuagint version, it's usually around 7500.
The Muslim calendar has 1440, though it uses a year of exactly 12 lunar months, without adding extra months to keep in sync with the seasons, as most other lunar calendars have.
Using Marcus Terentius Varro's calculating of the founding of Rome, it is 2772, and using the original Olympics, in summer of this year, the 3rd year of the 699th Olympiad will begin, making "Olympic year" 2793.
Turning to more recent marking points, this is year 227 of the French Republican calendar, and "Unix year" 50.
But what's in a day? A year?
First, when to begin a day. Sunrise? Noon? Sunset? Midnight?
All four conventions have been used by some people or other, though it's mostly astronomers who have used noon. They switched to midnight in 1925, to be like everybody else.
Whatever the convention, people at different longitudes will have days starting at different times relative to each other. A way out of that conundrum is to define a "prime meridian" as a longitude reference. Nearly 2000 years ago, Claudius Ptolemy defined one of the first, using the "Fortunate Isles" (The Canary Islands? The Cape Verde Islands?). Early-modern mariners and cartographers used several prime meridians before settling on the Greenwich one in the 1884 International Meridian Conference.
As to when to begin a year, here also, there are lots of conventions, scattered over the year. The Jewish year and the French Republican year begin around the autumnal equinox, the ancient Roman year originally began around the vernal equinox, our year begins a little after the winter solstice, the traditional Chinese year begins halfway between the winter solstice and the vernal equinox, etc. All northern-hemisphere seasons, I may add.
For counting the years, the first system used was the year-reign system. A modern version would go
- Donald Trump 3
- Queen Elizabeth II 68 -- Theresa May 4, Justin Trudeau 5, Scott Morrison 2, Jacinda Ardern 3
- Emmanuel Macron 3
- Frank-Walter Steinmeier 3 -- Angela Merkel 15
- Vladimir Putin II-7
- Emperor Akihito 30 -- Shinzo Abe 8
- Xi Jinping 8
- Ram Nath Kovind 3, Narendra Modi 6
- ...
As with longitudes, it is convenient to define some reference year that years are to be counted relative to. Several of them have been used, with ours being a calculation of when Jesus Christ was born.
The Jewish calendar has 5779, using a calculation of when the Universe was created according to the Bible. Archbishop James Ussher's calculation would give us 6023, and other calculations give us other year numbers. For the Masoretic version of the Old Testament / Tanakh / Hebrew Bible, it's usually around 6000, and for the Septuagint version, it's usually around 7500.
The Muslim calendar has 1440, though it uses a year of exactly 12 lunar months, without adding extra months to keep in sync with the seasons, as most other lunar calendars have.
Using Marcus Terentius Varro's calculating of the founding of Rome, it is 2772, and using the original Olympics, in summer of this year, the 3rd year of the 699th Olympiad will begin, making "Olympic year" 2793.
Turning to more recent marking points, this is year 227 of the French Republican calendar, and "Unix year" 50.