Is March more logical? Feb 29 + 1 year = Feb 28.
What’s the significance of 365? Each Earth year has just a smidge under 365.25 days.
365 days is what people commonly think of as a year. So if you're born Feb 29th and celebrate your birthday one year later (whether you call that 365 or 365.25), you land on Feb 28th. Then again, folks born between Jan 1 and Feb 28th of a leap year celebrate their birthdays 366 days later by calendar days.
Anyway, I'm not sure there's any more or less logical date to use and Feb 29th babies seem to choose both about equally:
> “I love when people ask me, ‘Do you celebrate on Feb. 28 or March 1?’” said Raenell Dawn, a co-founder of Honor Society of Leap Year Day Babies. “I get to tell them, ‘Both, because I can.’ But I’m a February baby; I was not born in March.” An informal poll of the society’s members showed about a 50-50 split between the two dates, said Ms. Dawn, who is celebrating her “Sweeter 16” by turning 64 this year.
https://www.nytimes.com/2024/02/28/style/leap-year-explained.html?unlocked_article_code=1.ZE0.d2UE.v0e0PbjW5NE6&smid=url-share https://www.nytimes.com/2024/02/28/style/leap-year-explained...
But 1 day is still 24 hours.
If you want to celebrate your birthday at the moment earth reaches the same spot around the sun as when you were born, then we’d all have the same issue - we’d have to celebrate it 6 hours later every year, reseting every 4 years.
February 29 is very much a new day… which simply doesn’t exist on non-leap years.
Think of it this way: if Feb 29 didn't exist that year, it would have been March 1.
If we're being scientific I guess all of us should move our birthday up by 1 day on leap years, but that seems annoying and not sure anyone really cares enough to.
By this logic, all birthdays would slowly drift as leap years pass.
Take DOB + n * 365.25 and then pick whatever day that falls in? That way it shouldn’t drift overall.
Though, I guess it would imply that what day of the year people celebrate on, would be off by one day on leap years compared to what it is on other years?
Similar to the recent standup maths video where the town did it's art installation incorrectly - the fence post problem / off by one.
https://youtu.be/FAdmpAZTH_M?si=r_INH_C5j9mbpJSh https://youtu.be/FAdmpAZTH_M?si=r_INH_C5j9mbpJSh
I asked JavaScript:
const { format } = Intl.DateTimeFormat("en-UK", { month: "short", day: "numeric" });
const date = new Date(2024, 1, 29);
console.log(format(date));
// 29 Feb
date.setYear(2025);
console.log(format(date));
// 1 Mar
const year = 1000 * 60 * 60 * 24 * 365.2425;
console.log(format(new Date(2024, 1, 29).getTime() + year));
// 28 Feb
I guess both are logical by some definition of logic.
You're begging the question. [1]
"Feb 29 + 1 year" is verbatim restatement.
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You can say Feb 29 + 365 days = Feb 28. (And Feb 29 + 730 days = Feb 27.)
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EDIT:
Note that in the context of birthdays, people use "calendar years," not "unit of time which is ~1 revolution around the sun."
Birthdays aren't celebrated every X million seconds after the moment of birth.
They are celebrated the same day each calendar year -- notwithstanding the fuzzy concept of "same day" for incongruent calendar years. There's no singuar right answer, but that is the core question: "what is the same day next (calendar) year?"
[1] https://en.wikipedia.org/wiki/Begging_the_question https://en.wikipedia.org/wiki/Begging_the_question
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> Feb 29 + 365 days = Feb 28.
Correct.
> And Feb 29 + 730 days = Feb 27
Incorrect. It's Feb 28 again. In a normal, non-leap year, if you add 365 days then you get back to the same date.
> Birthdays aren't celebrated every X million seconds after the moment of birth.
As a surprise for a friend of mine, I threw him a gigasecond party on the day he turned 1000 million seconds old. Yes he was surprised, and a good time was had by all.
Many people say: Happy turn around the sun! and 365 is not the length of a year is the length of some years so, who knows... I'm against time zones and pro 28 days months and a couple of free days :D
Feb 28 is definitely too early, you haven't lived a whole year yet since your birthday. So March 1 it is. It's not your birthday but you can celebrate having made it another year.
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Well 'year' can mean two different things though: 'calendar year' or 'solar year'.
Your calendar year birthday would be March 1 since one full calendar year has elapsed.
But Feb 28 is the nearest day to one full solar year, assuming you were born before about 6pm local time on Feb 29.
Two-day long birthday it is! :)
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