Leap Day miscellany

With two Tachyon authors (Tim Powers and Patricia A. McKillip) born on a leap day, it got us wondering about the day and the odds. Thankfully, VOX was thinking along similar lines.

Normally, the chance of being born on any given day is 1 in 365. But for leap babies, it’s four times that, plus an extra day. That comes out to 1 in 1,461. So only 0.07 percent of the world’s population shares a birthday with Adam.

Adam, who works on an oil pipeline in Ohio, technically has had more birthdays than his daughter. On February 29, he will mark his ninth real birthday. (In more conventional terms, he’s turning 36.)

So the odds have two Tachyon authors sharing a birthday on February 29th is pretty astronomical. Please don’t ask me to do the math.

In the United States, a person’s birthday during common years, or non-leap years, is likely March 1.

Piekarski says, and others echo, that renewing his license is a reliable nuisance. Department of Motor Vehicle employees, who likely glaze over after typing so many dates, routinely print forms saying he must renew his license on 2/29/2017, a date that obviously doesn’t exist.

Espasito has even seen DMV workers try to print IDs with the wrong birthdate listed. “I always get flagged, I always have to produce my birth certificate,” she said.

Web forms frequently cause problems, too. Often, drop-down boxes simply don’t have more than 28 days listed under February. In those cases, most people just fudge it and hope for the best.

But the stakes are higher on Facebook. Unlike many less sophisticated websites, Facebook does recognize February 29 as a valid birth date. But for years, the social network didn’t know how to adapt during non-leap years.

On February 28, it would alert users that their friend’s birthday was coming up the next day. But on March 1 … nothing.

“That’s how I knew who my real friends were,” Haney said.

Most leap year babies say Facebook has since fixed the glitch, and, per the government’s example, it defaults to March 1.

For more insights into Leap Day births, read the rest of the fascinating VOX article.