Why 4/20/2024 is the 'stoner eclipse,' won't happen again for 1,000 years

This year's high holiday will be extra trippy.

April 20, known colloquially as 420 or a holiday for marijuana enthusiasts, falls on April 20, 2024, this year, or 4/20/2024, making it a palindrome. Read it from left to right or right to left, it's the same.

The hazy occurrence will take place once every millennium, with the next falling on 4/20/3024.

Here's everything to know.

What is a palindrome?

A palindrome is a word or phrase that reads the same backward as it does frontward, with common examples being "racecar," "madam" and "was it a car or a cat I saw?"

Where did the 420 holiday come from?

Though there is no officially agreed upon story about the holiday's origins, plenty of popular theories exist – perhaps the most famous involving a cohort of teenagers in California.

The group of high schoolers from Northern California's San Rafael High School dubbed themselves the "Waldos." And in the early 1970s, they used to gather at 4:20 p.m. to smoke cannabis.

“We weren’t stupid stoners,” Steve Capper, 68, an original Waldo, told USA TODAY, pointing to a certificate for exceptional achievement and citizenship he received in school. He explained that they chose 4:20 p.m. because it was the time everyone was free to meet.

The time stamp became code for the act of smoking weed, and eventually spread beyond the Golden State's borders to none other than The Grateful Dead.

Dave Reddix, a member of the Waldos, told Time magazine in 2017 that the band helped popularize the term during his tenure working as a roadie for bassist Phil Lesh. Time reports that during a December show in 1990, some Deadheads in Oakland distributed flyers inviting people to smoke “420” at 4:20 p.m. on April 20.

The flyer fell into the hands of Steven Bloom, a reporter at The High Times. The following year the popular cannabis publication printed that flyer and a new observance was born.

Though other theories exist about the origins of 420, including references to a California police code and a Bob Dylan song, the Waldos have remained adamant that they are the true architects of the holiday.

Our favorite social media reactions to the 4/20/2024 palindrome

Weed lovers have taken to social media to celebrate the rarity of the 4/20/2024 occasion, with one Reddit user saying, “It’s the only time it’ll happen in history. Like, a stoner eclipse!”

Here are some of our other favorite online reactions to the (puff, puff, pass) palindrome.

This article originally appeared on Cincinnati Enquirer: Why 4/20/2024 is a 'stoner eclipse,' won't happen for 1,000 years