Why we mark a New Year January 1?

[Moreno]

Which astronomical event is associated with 1 January that we mark a New Year start from this date? Wouldn't it be more logical to mark it from 23 December when the daytime starts to increase? What do you think about possibility to shift it on 23 Dec.?

[zapatos]

Quote

In 45 B.C., New Year’s Day is celebrated on January 1 for the first time in history as the Julian calendar takes effect.

Soon after becoming Roman dictator, Julius Caesar decided that the traditional Roman calendar was in dire need of reform. Introduced around the seventh century B.C., the Roman calendar attempted to follow the lunar cycle but frequently fell out of phase with the seasons and had to be corrected. In addition, the pontifices, the Roman body charged with overseeing the calendar, often abused its authority by adding days to extend political terms or interfere with elections.

In designing his new calendar, Caesar enlisted the aid of Sosigenes, an Alexandrian astronomer, who advised him to do away with the lunar cycle entirely and follow the solar year, as did the Egyptians. The year was calculated to be 365 and 1/4 days, and Caesar added 67 days to 45 B.C., making 46 B.C. begin on January 1, rather than in March. He also decreed that every four years a day be added to February, thus theoretically keeping his calendar from falling out of step.

https://www.history.com/this-day-in-history/new-years-day

[swansont]

The day of the solstice can vary. 21st or 22nd, typically, so they day that daytime begins to increase in the northern hemisphere is not fixed.

[mathematic]

From Wikipedia

In AD 567, the Council of Tours formally abolished January 1 as the beginning of the year. At various times and in various places throughout medieval Christian Europe, the new year was celebrated on December 25 in honor of the birth of Jesus; March 1 in the old Roman style; March 25 in honor of Lady Day and the Feast of the Annunciation; and on the movable feast of Easter. These days were also astronomically and astrologically significant since, at the time of the Julian reform, March 25 had been understood as the spring equinox and December 25 as the winter solstice. (The Julian calendar's small disagreement with the solar year, however, shifted these days earlier before the Council of Nicaea which formed the basis of the calculations used during the Gregorian reformof the calendar.) Medieval calendars nonetheless often continued to display the months running from January to December, despite their readers reckoning the transition from one year to the next on a different day.

[Moreno]

1 hour ago, swansont said:

The day of the solstice can vary. 21st or 22nd, typically, so they day that daytime begins to increase in the northern hemisphere is not fixed.

The solstice always happens either 21 Dec. late evening or 22 Dec. early morning making the difference between these two days insignificant. In this way 23 Dec. is the day which could be taking for the daytime increase mark. This is in Northern hemisphere of course, but I think it's still better to a have a New Year connected to some astronomical event than to none at all.

[swansont]

5 minutes ago, Moreno said:

The solstice always happens either 21 Dec. late evening or 22 Dec. early morning making the difference between these two days insignificant. In this way 23 Dec. is the day which could be taking for the daytime increase mark. This is in Northern hemisphere of course, but I think it's still better to a have a New Year connected to some astronomical event than to none at all.

At work, I always put up a sign celebrating the perihelion

[zapatos]

24 minutes ago, Moreno said:

The solstice always happens either 21 Dec. late evening or 22 Dec. early morning making the difference between these two days insignificant. In this way 23 Dec. is the day which could be taking for the daytime increase mark. This is in Northern hemisphere of course, but I think it's still better to a have a New Year connected to some astronomical event than to none at all.

Wait. Which astronomical event happens on December 23?

[OldChemE]

The bottom line is that there is not astronomical significance.  But-- if you want to count years, you need to start somewhere.  Jan 1 as the beginning of the new year is an artifact of human history that is currently accepted by a large segment of human population.  The rest of the universe doesn't care one way or the other.

[Moreno]

5 hours ago, zapatos said:

Wait. Which astronomical event happens on December 23?

The first firm day after the winter solstice.

[zapatos]

"The first firm day after the winter solstice" is not an astronomical event.

However, if you want to consider days after astronomical events as candidates for celebrating the new year, then I would like to propose we mark the New Year as the 9th firm day after the winter solstice, since it also has historical significance and coincides with the period named after the God of beginnings. Very appropriate for a new year.

[dimreepr]

 

7 hours ago, Moreno said:

The first firm day after the winter solstice.

A UK tax year runs from 6 April to the following 5 April.