Here are the true stories behind your favorite Christmas songs

As always happens right before Christmas, the Billboard Hot 100 chart is filled with holiday songs this week. We're getting in the Christmas spirit by bringing you fun stories behind some of your favorites!

Here Comes Santa Claus

This is a story of when a singing cowboy got upstaged by Santa Claus on Hollywood Boulevard. In the Christmas season of 1949, Gene Autry's version of "Rudolph the Red-Nosed Reindeer" was the No. 1 song in America. But the previous year, Autry had a top 10 hit with another Christmas song that he wrote after his experience in the Hollywood Christmas Parade.

In 1946, Autry rode as grand marshal in the Hollywood Christmas Parade, which was then known by a different name. Shopping malls weren't invented yet, and the merchants along Hollywood Boulevard wanted to lure as many holiday shoppers as possible. They started marketing the district as Santa Claus Lane and brought in A-list stars like Autry to appear in what was then called The Santa Claus Lane Parade.

Even though Autry was a huge star at the time, he was upstaged by someone else. As he rode down "Santa Claus Lane," he heard the chorus of kids shouting in delight - but not for him, as his widow Jackie Autry later explained: "He heard the kids yelling, 'Here comes Santa Claus, here comes Santa Claus because Santa Claus was on a float just behind Gene."

The excited words of those kids, "Here comes Santa Claus," gave Autry the idea for what became a top 10 hit at the time and has endured as a beloved Christmas classic ever since.

Jingle Bells

This beloved Christmas song was actually written for a different holiday and would later become part of the greatest prank ever pulled in outer space.

Long Before Shroeder played "Jingle Bells" in "A Charlie Brown Christmas," and well before Ralphie's family sang it in "A Christmas Story," "Jingle Bells" is believed to have first been performed in 1857 at a Sunday school concert on Thanksgiving. It was originally titled, "The One Horse Opened Sleigh" by composer James Lord Pierpont, who'd later serve in the Confederate Army.

Now among the most recognizable songs on Earth, Jingle Bells also holds a unique record in outer space. Shortly before Christmas in 1965, NASA's Gemini 6 crew reported seeing a UFO that resembled Santa and his reindeer

"This is Gemini 6. We have an object that looks like a satellite going north to south up in a polar orbit," the astronauts were recorded saying.

Then, astronauts Wally Schirra and Tom Stafford surprised everyone at Mission Control suggesting the UFO was trying to make contact.

"It looks like he's trying to signal something," then "Jingle Bells" started to play! Schirra and Stafford then revealed they'd snuck bells and a harmonica onboard for their Christmas prank, which also made history as the first live music ever performed in space.

Last Christmas

Wham! blended the classic 80s synthesizer sound with holiday sentimentality for "Last Christmas." It's among America's favorite Christmas songs even though some people spend the entire holiday season hoping to never hear it.

George Michael wrote the song in his childhood bedroom while visiting his parents. It's a Christmas song that isn't about Christmas at all. "Last Christmas" actually tells the story of a difficult breakup.

Thirty five years later, Michael gave Emma Thompson his blessing to write a movie based on the lyrics, and we got the 2019 Christmas rom-com, "Last Christmas," starring Emilia Clarke and Henry Golding.

But the song is not universally loved. Each year, some people try to avoid hearing it all throughout December in a game called "Whamageddon." The rules are simple: If you hear "Last Christmas" anywhere, you're out of the game and have to post online with the hashtag #Whamageddon.

But for many, it's a holiday favorite covered by stars like Taylor Swift, Gwen Stefani and Ariana Grande.

After George Michael's death on Christmas Day 2016, people started streaming his original Wham! version like never before. In 2018, the song, which wasn't originally released as a single in the U.S. made its debut on the Billboard Hot 100 Chart.

All I Want for Christmas is You

There's no bigger holiday hit then Mariah Carey's "All I Want for Christmas is You." The song, first released in 1994, is No. 1 on The Billboard Hot 100 Chart again this week, making it the first song ever to top the chart in three different years. And it's now officially gone platinum 10 times over, making it the first holiday tune to ever be certified diamond. When Billboard put out a list of its 100 greatest holiday songs this year, Mariah Carey's "All I Want for Christmas is You," was of course No. 1.

This year, Mariah began her Christmas season right after Halloween, posting video at midnight on Nov. 1 smashing pumpkins to declare Halloween over and Christmastime upon us.

Her song continues to get more and more popular each year. In fact, 25 years after its release, the song topped the Billboard Hot 100 for the first time - the first Christmas song to be No. 1 in America since the Chipmunks in the 1950s.

And talk about a wish come true: Carey has reportedly earned well over $60 million in royalties from her upbeat holiday hit.

"When I first wrote it, all I did was critique myself. 'Why did I do that? Why is it like that? I wish I had fixed that.' And now there've been so many different versions of the song that I'm like you know what? I can live with this and love it and accept it and embrace it as part of my Christmas tradition every year," Carey said in an interview with the Associated Press.

One of those different versions is a memorable scene in the movie "Love Actually." But it's not all "love actually" for the song: A bar in Texas this year put a sign on the jukebox saying "Mariah can only be played once a night."

Someone wrote on Twitter: "Is this the war on Christmas I've heard about," and Mariah responded, posting a photo of herself in armor on a battlefield - ready for a fight! Clearly, you don't mess with the queen of Christmas.

Have Yourself a Merry Little Christmas

Movie legend Judy Garland was first to perform the melancholy holiday classic, "Have Yourself a Merry Little Christmas" - but not in a Christmas movie.

It was the MGM musical "Meet Me in St. Louis." Garland's character was trying to cheer up her little sister on Christmas Eve, their family devastated to be moving to New York City, leaving behind their beloved hometown of St. Louis.

Judy Garland actually thought the song was too sad and asked for the original lyrics to be changed. It was originally, "Have yourself a merry little Christmas. It may be your last. Next year we may all be living in the past."

After Garland lobbied for a re-write, it was switched to: "Let your heart be light. Next year all our troubles will be out of sight."

And with that, Hollywood history and holiday history were made!