I propose we introduce leap year reform.
(It'll probably never actually happen. I'm just proposing it for the sake of discussion.)
The Gregorian calendar was introduced because it was considered important to keep the calendar exactly synchronised with the seasons. (Otherwise, why bother switching from the Julian calendar to begin with?)
But we now have a better understanding of the length of the seasonal cycle (tropical year) than they did back in the sixteenth century, so why not use that knowledge to improve the leap-year rule to make it even more exact?
Instead of the current practice of skipping a single leap year in three centuries out of four, I propose we simply skip a leap year once every 128 years.
Skip-Year Rules:
(I'm using “skip-year” to mean any year divisible by four which isn't a leap year.)
Let's compare the accuracy of these systems:
Clearly the new calendar would be far more accurate in the long term than the Gregorian calendar.
Except that the error rate I've given assumes that the length of the mean tropical year will stay the same. But in reality it's slowly getting smaller, so the error-rate I've calculated isn't really representative of long-term performance.
(Strictly speaking, the length of the mean tropical year does stay the same. It's just that the days are getting longer due to the gradual slowing of the earth's rotation. But since we measure the length of the year in days, this is effectively the same thing as the year getting shorter.)
The mean tropical year has become about 0.000121 days shorter over the last 2000 years. Assuming that it continues to change at the same rate, the mean tropical year would become exactly identical to the average year under the new calendar somewhere around 2051 AD.
After that, the new calendar would start becoming more inaccurate, just like the Gregorian calendar. But it would always be more accurate than the Gregorian calendar.
For example, the new calendar won't reach the same level of inaccuracy that the Gregorian calendar currently has until somewhere around 7180 AD. But by that point, the Gregorian would be twice as inaccurate than it currently is.
If we were to switch to this new calendar, the only difference in our lifetimes would be that the next skip-day would be in 2048 instead of 2100.
I've mostly worked this all out because I'm creating a new calendar, just for my own amusement. I don't expect my new calendar to ever become accepted, there are already plenty of reform calendars out there, but I thought the idea of applying my alternate leap-year rule to a real-life calendar might be interesting to talk about.
Anyone have any better suggestions for leap years?
Can anyone point out any flaws in this idea?
Anyone think that we should just not bother about it, and go back to the Julian calendar rule which made every year divisible by four a leap year?
Or maybe we should get rid of leap years altogether, and make the calendar year exactly 365 days? Would it really matter if the calendar drifted ahead of the seasons by up to 25 days in your lifetime?
(Putting this thread under in the Non-USA & General Politics, because trying to change the calendar probably falls under the heading of General Politics.)
(It'll probably never actually happen. I'm just proposing it for the sake of discussion.)
The Gregorian calendar was introduced because it was considered important to keep the calendar exactly synchronised with the seasons. (Otherwise, why bother switching from the Julian calendar to begin with?)
But we now have a better understanding of the length of the seasonal cycle (tropical year) than they did back in the sixteenth century, so why not use that knowledge to improve the leap-year rule to make it even more exact?
Instead of the current practice of skipping a single leap year in three centuries out of four, I propose we simply skip a leap year once every 128 years.
Skip-Year Rules:
| Julian Calendar | None. |
| Gregorian Calendar | Any year divisible by 100 but not 400. |
| New Calendar | Any year divisible by 128. |
(I'm using “skip-year” to mean any year divisible by four which isn't a leap year.)
Let's compare the accuracy of these systems:
| Calendar | Avg. Year Length | Error Rate |
| Julian Calendar | 365.2500000 days | 1 day per 128 years |
| Gregorian Calendar | 365.2425000 days | 1 day per 3223 years |
| (Mean Tropical Year) | 365.2421897 days | (N/A) |
| New Calendar | 365.2421875 days | 1 day per 454545 years |
Clearly the new calendar would be far more accurate in the long term than the Gregorian calendar.
Except that the error rate I've given assumes that the length of the mean tropical year will stay the same. But in reality it's slowly getting smaller, so the error-rate I've calculated isn't really representative of long-term performance.
(Strictly speaking, the length of the mean tropical year does stay the same. It's just that the days are getting longer due to the gradual slowing of the earth's rotation. But since we measure the length of the year in days, this is effectively the same thing as the year getting shorter.)
The mean tropical year has become about 0.000121 days shorter over the last 2000 years. Assuming that it continues to change at the same rate, the mean tropical year would become exactly identical to the average year under the new calendar somewhere around 2051 AD.
After that, the new calendar would start becoming more inaccurate, just like the Gregorian calendar. But it would always be more accurate than the Gregorian calendar.
For example, the new calendar won't reach the same level of inaccuracy that the Gregorian calendar currently has until somewhere around 7180 AD. But by that point, the Gregorian would be twice as inaccurate than it currently is.
If we were to switch to this new calendar, the only difference in our lifetimes would be that the next skip-day would be in 2048 instead of 2100.
I've mostly worked this all out because I'm creating a new calendar, just for my own amusement. I don't expect my new calendar to ever become accepted, there are already plenty of reform calendars out there, but I thought the idea of applying my alternate leap-year rule to a real-life calendar might be interesting to talk about.
Anyone have any better suggestions for leap years?
Can anyone point out any flaws in this idea?
Anyone think that we should just not bother about it, and go back to the Julian calendar rule which made every year divisible by four a leap year?
Or maybe we should get rid of leap years altogether, and make the calendar year exactly 365 days? Would it really matter if the calendar drifted ahead of the seasons by up to 25 days in your lifetime?
(Putting this thread under in the Non-USA & General Politics, because trying to change the calendar probably falls under the heading of General Politics.)
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