Dylan Moulton is turning 12 on Thursday but his family jokes that he is turning 3. Dylan, who loves to be outside hunting, fishing, playing lacrosse and riding his dirt bike, celebrates his birthday on Feb. 28th and March 1st on the years without his real birthday. Derek Davis/Staff Photographer

Dylan Moulton gets to properly celebrate his birthday just once every 1,461 days, a number he has put to memory because it happens so infrequently.

The Scarborough Middle School student is turning 12 years old Thursday. But he will only be celebrating his third “real birthday.” He’s a leap day baby, one of an exclusive club of people born on Feb. 29, a date that occurs only once every four years.

“I actually have a real birthday this year, when I’ll be 3,” said Dylan, who will sometimes use his special birthday to his advantage.

“If someone says ‘Act your age,’ I’ll say, ‘I am. I’m 2.’ But then my grandma will say, ‘That’s baloney,’ ” Dylan said, grinning as he tried to balance on a Onewheel electric skateboard.

The reason leap year exists is as old as time – the Earth’s trip around the sun takes slightly longer than 365 days, clocking in at precisely 365.24219 days per year. That means calendars need to add a day once every four years – leap day – to adjust for the discrepancy and keep the calendar and the seasons in sync with the orbit.

“I learned that in fifth grade, when we were learning about solar system stuff,” said Dylan, who is a sixth-grader.

Astute mathematicians will note that 365.24219 is not exactly 365.25. Won’t leap years – over the long arc of history – also cause errors in the calendar?

Eventually, yes.

Adding a Feb. 29 to the calendar every four years adds an extra 44 minutes to the year. But there’s a fix for that, too.

Leap year is skipped every time the year is divisible by 100 and not evenly divisible by 400. There was no leap day in 1700, 1800 and 1900, but 2000 had one.

The next time leap year will be skipped is 2100. So instead of Dylan celebrating his 22nd “real birthday” in 2100 – he’ll be 88 in calendar years – he’ll have to wait another four years for Feb. 29 to come around again.

Like other leap day babies, Dylan doesn’t actually pass up birthday parties in between leap years. He celebrates the day before or after when he has to.

But for now, Dylan is looking forward to a rare proper birthday filled with presents, strawberry ice cream cake (with 15 candles signifying 12 and 3), and a trip with friends to a trampoline park.

His mother, Rebecca Flaherty, said that when she was pregnant with Dylan, her due date was Feb. 29, but she thought he would arrive early because he was so active in the womb. She went into labor on Feb. 28, but Dylan was not born until 4:22 a.m. on Feb. 29.

So how many Maine people celebrate leap day birthdays? The statistics are not precise, but roughly 30 babies are born on a leap day in Maine, which would equal about 400 leap day babies having been born in the state over the past 50 years.

Meagan Rudge, a fitness coach at Orangetheory Fitness in Portland, prepares to lead her class on Wednesday. A leap day baby, she’ll be turning 9, or 36, on Thursday. She plans to go to a trampoline park, play arcade games and go to a climbing gym with her fiancé and friends. “I’m going to tap into my youthful side, since I’m turning 9,” Rudge said. Ben McCanna/Staff Photographer

Meagan Rudge, of Woolwich, is celebrating her ninth leap day birthday Thursday. Rudge, who is turning 36, said she’s used to people not knowing exactly what to say when it’s close to her birthday in non-leap years.

“People will say, ‘Happy almost birthday’ or ‘Happy sort-of birthday,’ ” said Rudge, who leads fitness classes and does personal training at Orangetheory Fitness in Portland. “I’ll say, ‘Sort-of thank you.’ ”

Rudge said it’s gotten better in recent years, but it used to be a problem when filling out online forms that needed a birthdate.

“You would scroll down, and you couldn’t choose Feb. 29,” Rudge said. “Signing up for anything that needed my exact age would often flag it as an error.”

Rudge said she plans to go to a trampoline park, play arcade games and go to a climbing gym on her birthday with her fiancé and friends.

“I’m going to tap into my youthful side, since I’m turning 9,” Rudge said, laughing.