Once every 1,461 days, sometimes, we have a day on the calendar that we don't normally have.

Leap Day.

This extra day is a necessity if our calendars are to be kept in sync with the orbit of the Earth around the Sun,

but it can also cause problems with people and computers.

Nonetheless, whatever problems that might cause are far less than some of the alternatives,

which would require leap weeks and even leap months.

Learn more about leap years and leap day and the significance of February 29th on this episode of Everything Everywhere Daily. If you've listened to this podcast long enough, you know that I have a thing for calendars.

I've done episodes on everything from how we got

the days of the week to the Gregorian calendar to the months. So there is no way that I was going

to let February 29th go by without doing an episode on it, especially considering that this is the first

February 29th that I've experienced since starting this podcast.

I've touched on why there is a February 29th in previous episodes, but let me briefly restate the reason for it here.

The problem is that our basic units of time, the day in the year, are determined by astronomical

events, which are not evenly divisible by each other.

I've read many different proposals for different calendar systems, and while some of them do

have their merits, they can't escape this fundamental problem.

Days do not divide evenly into a solar year.

Our current calendar, the Gregorian calendar, is based on a solar year.

That means it tries to get the seasons and the solar events such as the solstices and the equinoxes

at the same time each year.

However, the Gregorian calendar was a modification of the Julian calendar and the

Julian calendar was designed to replace the Roman calendar, which was truly awful.

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