Why isn't the solstice New Years Day?

Yeah, except that New Years Day is exactly seven days after Christmas which ruins the story unless there is some reason for pegging Jan 2 to being 8 days after Christmas. The story sound sounds like hokum anyway.The calendar has been adjusted a few times because of the mismatch between 365.25 days and the actual length of a year which is more like 365.2422 days. Astronomy hobbyists know that in the calendar reform of 1582, ten whole days were skipped as part of the transistion betweeen the Julian and Gregorian calendar.I believe the old Hebrew calendar was based on the moon, which is the reason why the date of Easter flies around the calendar so much.Finally, anyone who is absolutely positive that Christ was born on the Winter Solistice as opposed to any other time of the year is probably someone you need to take a couple of steps away from. There is likely more than one thing wrong with them.Edited by NoNukes, : No reason given.

Don't calendar systems imply recording?There is no particularly good reason to start the year on the Winter Solstice. Why not start the year on an equinox? Or on the date of Earth's perihelion, which is actually only about two days later than New Years Day?And doggone it, the Winter Solistice is never any later than December 23, and even that occurs quite rarely. I suspect calendar tinkering may have something to do with the slippage to December 25th.People may have used calendars starting at Winter Solstice, but the Julian and Gregorian calendars did not work that way.

In my brief search, I have not found any references that set Christmas up as being the day of winter solstice. As best as I can tell, somewhere in the 4th century the date was set to December 25th.The date or a connection with the solstice is not derived from the Bible. Everyone seems so sure that the chosen date must be a solstice based date that has slipped with calendar inaccuracies, but I cannot find any references supporting anything like that.People who care about the Julian calendar celebrate Christmas on Jan 6 of all dates. Which would have pretty much assured that your calendar would be useless today. A calendar should take into account the length of the year and the passage of days. If it does not do both, it isn't worthwhile. Back in the days of the early solar system the length of a day was surely something different than it is now. Surely the day was much shorter at a time right after we acquired our moon.

That does accurately reflect the Jewish accounting. The scheme is circumcision on the 8th day of life, and not 8 days after birth which I believe was the originally stated counting. Yes, but getting barely into the second week could not have mattered all that much over say the seventh day. And I suspect that sawing away on the new born's johnson did not help much with the infant mortality rate.

I think you are neglecting the ten days that were removed from the calendar when the Gregorian calendar was introduced. I think the answer to your question is that the standard argument is wrong.As I understand the problem, Christmas was set to December 25th in the 4th century, so the question is whether that Solstice was closer to Christmas around 350 AD.Here is a rough estimate:If we backtrack the Solstice from today back to 1582 using the current leap year count, we find that the each year is a tiny bit too long (0.2425 vs 0.24219 days per year). Over (2013-1582)*(0.2425-0.24219) equals 0.13 one day of drift. Since our year is slightly too long on average, that means Solstice back in 1582 was 0.13 days later than now.Alternatively, and more accurately we can see that we've had 105 leap year days in the 431 years between 1582 and 2013. Without any leap year days, the Solstice would advance over time because our year would be exactly 365 days. 0.24219*431 = 104.4 days earlier by 1582. Adding in the 105 leap years, and there is a net move of 0.6 days later.To get back to the Julian calendar, we add back the ten days making the Solstice date 9.4 days earlier than today, then we assume a straight leap year every fourth year back tracking to 350 AD.308 leap years out of 1232 years or exactly 365.25 days per year for the Julian calendar and 365.24219 for the sun. So as we go back in time the date of winter Solstice gets later. 1232 * (0.25-0.2422) = 9.6 days later using the Julian calendar. Adding in the 9.4 days earlier from the Gregorian calendar produces a net offset of about 0.2 days.By my calculation, the relationship between the winter Solstice and Christmas in 350AD is pretty much the same as it is today.Of course while I was looking up some of the numbers, I noticed that the Roman Church at some times assumed a date of April 25th for the Vernal Equinox. If they were making astronomical, mistakes like that, then maybe they did think Dec 25th was the winter solstice.

I think this assumption is really shaky, and likely wrong. For one thing, at the time the Gregorian calendar reform came up, the Winter Solstice had moved to December 11th. The reform corrected it back to December 21st.Secondly, the date Christmas was set to December 25th was around 350AD and not back in 45 BC. BC???Edited by NoNukes, : No reason given.

The winter solstice is an annually occurring, astronomically determined instant in time. If people using the Gregorian (or Julian) calendar regarded the 25th as the solstice, I would not consider that to be just their view or opinion. They were wrong. Wikipedia suggests in the 4th century around 350. Edited by NoNukes, : No reason given.

Okay What tradition do you think that was? Celebrating Christmas on the solistice? On December 25th? On the date that other people were celebrating whatever? I think for this particular nit-picky discussion it matters. Your explanation is not quite right. If the issue were about the length of the year we would handle it using some kind of leap year like scheme.The issue solved with leap seconds revolves around the mean solar day not being an even number of seconds long as the second is currently defined. A clock day of 24 hours is 86400 seconds, but the average length of a day is 86400.002 seconds long. That 0.002 seconds per day accumulates to about approximately one second over 18 months.We could define the second to be 1/86400 of a mean solar day. That would be close enough for most purposes, and the leap second problem would disappear.The problem with redefining the second is that the length of a day also changes over time by something quite a bit smaller than 0.002 seconds per day, so we really don't want to redefine the second based on the earth's rotation. I can remember going 'round and round' on this issue with a creationist.