Is the world going to end right in the middle of the upcoming holiday season? While that wouldn't be good for retail sales, many people feel that Dec. 21, 2012 is a date that will linger in our minds forever -- assuming we all survive the calamities that are supposedly headed our way.

The ancient Mayan civilization calendar is believed to end this year on Dec. 21. And somehow, through word-of-mouth, movies, books, the Internet, etc., a cult-like belief system has sprung up in our culture suggesting any number of awful things will take place on that date.

Some of these include:

• An unknown planet on a collision path with Earth.
• A close encounter between Earth and a black hole in deep space.
• More natural disasters around our planet.
• A shifting of Earth's magnetic poles.

But where did all of these rumors actually start?

Many believe it goes back thousands of years to the ancient Sumerian culture who reportedly discovered a twelfth planet they called Nibiru -- aka Planet X -- which was predicted to have a close encounter with Earth in 2003.

When that didn't happen, a new Doomsday was moved to December 2012.

On the other hand, there are some who believe the December date heralds not doom and gloom, but a more positive transformative experience for Earth and its inhabitants.

It all sounds rather sketchy, especially to a scientist.

"It's all a hoax, and it's based on absolutely no factual information. None of the things that are supposed to happen are real, and so it's kind of hard to even have a scientific discussion about what they're worried about because there's no science there," said David Morrison, a leading space scientist and director of the Carl Sagan Center for Study of Life in the Universe at the SETI Institute in California.

Watch this Doomsday video with David Morrison

While SETI scientists are involved with the ongoing search for extraterrestrial intelligence, they also want to quiet any fears the public has about the alleged Doomsday.

To that end, Morrison created a special Doomsday 2012 Fact Sheet in September that's posted on both SETI and NASA websites.

According to this fact sheet, "opinion polls suggest that one in 10 Americans worry about whether they will survive past December 21 of this year."

"Think about that. It means when you walk down the street and look around, there are 25 million people who presumably have no stake in anything because their world's going to end in [December]. That is scary," Morrison told The Huffington Post.

When Morrison was researching information for his Doomsday fact sheet, he didn't find anything that confirmed that the Mayans left us any dire predictions.

"The Maya scholars I've talked to say flat out they did not make any such predictions. The question then is does their calendar end? Well, that's not true, either, because there are written references to dates that are hundreds of years in the future, which indicates the calendar must keep going," he said.

"So, this is not a Maya thing -- they don't think anything bad's going to happen, and it's only meaningful if you believe the Maya could predict the future."

Morrison assured HuffPost that he's not building a bunker in his backyard to protect himself and his loved ones.

"I am not. And that's a whole other thing that's part of this mythology about how the government has been frantically building bunkers to house millions of people underground -- the elite, of course, not the rest of us. And that's just crazy."

Check out this video about the ancient Sumerians and Planet X

There is, however, one part of this whole Doomsday scenario that the NASA/SETI scientist is very concerned about.

"I think it is wrong to put out a website or make a YouTube video in order to frighten children," he said. "That is something we should be truly offended by. And my main concern is that children have said they are contemplating suicide. A science teacher in Stockton, Calif., said the parents of two of her students told her they were planning to kill the children and themselves in a family suicide before the 21st of December.

"For children who are asking, 'Will Christmas come this year, Daddy?' I think that's evil," Morrison said.

That's also a concern of Jonathan Alpert, a New York City-based psychotherapist and author of "Be Fearless: Change Your Life in 28 Days."

"I have adults who see me and have beliefs that the world is ending, and they have kids, so it permeates into the kids' thinking," Alpert told HuffPost. "They're instilling fear in their young ones. Kids learn from adults, so if you're a kid and you witness your parents getting frenetic and anxious around the end of the world, and they're hoarding water and this and that, then naturally you'll develop a similar response."

Alpert says that, even though scientists reject the Doomsday scenario, it still affects people.

"In a way, it's like a folklore," Alpert explained. "People want to feel like they're part of something. They want to believe in things, even if those things are somewhat outrageous. There's a feeling of belonging-ness."

To help parents and children cope with any Doomsday issues, Alpert offers some advice.

"I would say stick with the facts. Kids are impressionable and easily influenced and ideas can be perpetuated in an unhealthy way, so parents should certainly take an active role in knowing what their kids are being exposed to and subsequently re-educating their kids."