leap year

BISSEXTILE: from latin "bis" (repeat) and "sextus" (sixth).
Sixth day before the "calendes de mars" (Honnor to God Mars festival in the Julian calendar), 24th february, was doubled, every four years.
Now it's 29th feb...easier to add on a calendar?

I have learned something today!

Thank you for the replies.

BTW, Sixth day before the calendas martias is 23th February; not 24th.

But in the Roman calendar, they counted backwards inclusively. So the Roman date "ante diem VI Kal. Mart." (ie 6th day before the Kalends of March) is indeed 24th Feb. This presumes 28 days in Feb - before Augustus adjusted the calendar Feb had 30 days.

See http://en.wikipedia.org/wiki/Roman_calendar

I seem to recall there was a leap second a few years back to make up for planetary irregularities.

iviehoff said on #5: But in the Roman calendar, they counted backwards inclusively.

Right. I forgot that fact. My apologies.

Kerouac2 said on #6: I seem to recall there was a leap second a few years back to make up for planetary irregularities.

Are you talking about year 2000?
You can read [here|en.wikipedia.org/wiki/Leap_year#Gregorian_calendar] about it.

Leap seconds are a lot more common than I thought according to this.

Kerouac2 said on #8: Leap seconds are a lot more common than I thought according to this.

Thanks for posting. I wasn't able to identify what was a leap second when I wrote my post #7. I was translating leap to Spanish using the same word we use for leap in leap year and I couldn't make sense of it. Thanks to your link, I already know what's a leap second... and the translation to Spanish. Thank you!

Leap seconds are a lot more common than I thought according to http://en.wikipedia.org/wiki/Leap_second

An average of 6 per decade, due to the modern SI atomically defined second being slightly undersized in comparison to the astronomical second defined as 24x60x60 per mean solar day. And as you will also read there, there is a proposal to the ITU to abolish leap seconds, which has quite a high chance of succeeding, being backed by the Americans. It is convenient for the operation of certain satellites and other equipment needing very precise clock synchronisation to abolish it. They were going to vote on it in Jan 2012, but have put the vote back to 2015.