Leap Year Doesn't Actually Happen Every 4 Years

Every four years, we get to celebrate leap year, with an extra day tacked onto the end of February to keep our calendar in sync with the solar year—the amount of time it takes for the Earth to revolve around the sun, or about 365.242159 days, per the Christian Science Monitor. Julius Caesar attempted to make up for that extra 0.242159 days every year by simply adding one whole day every four years, but that turned out to be a tad too much, an incremental change that had the calendar 10 whole days out of whack by 1582. Pope Gregory XIII tried to even things up by mandating that leap year not fall on centennial years, unless that year was divisible by four (so 2000 was considered a leap year, but not 1900). Which made things better but still "not a perfect fit," a University of Virginia astronomer says. (A Los Angeles Times graphic shows how hard it is to actually figure this stuff out.) Other leap-year morsels:

• Despite the date's unique status, many parents don't want their kids to be leap babies (aka "leaplings" or "leapers"), FiveThirtyEight finds. Find out the lengths pregnant women go to to avoid that birthdate.

• Quartz checks out some of the ways leap babies celebrate—and how they decide whether to mark their big day on Feb. 28 or March 1.
• Tradition holds that during leap years, women are actually encouraged to propose to men on Feb. 29. The Guardian picks the brains of some on how they feel about this custom, including one woman who calls the entire concept of marriage "patriarchal."
• The Portland Press Herald offers insight into Smithfield, "Maine's Only Leap Year Town," incorporated on Feb. 29, 1840. Which makes it 176 years old Monday—or is that 43?

(Meet America's oldest living leap-year baby.)