WASHINGTON — When the summer solstice arrives Wednesday, it will mark six months until the winter solstice on Dec. 21, when, according to some people’s reading of the Mayan Long Count calendar, the world will be destroyed.

Scientists and archeologists have debunked the doomsday theory, but it remains alive and well in popular culture.

“People who are not specialists in the Maya calendar have taken a few quotes and a few misunderstandings by scholars, and they’ve picked it up and run with it,” says Simon Martin, co-curator of a “Maya 2012: Lords of Time” museum exhibit in Philadelphia. “So it becomes somewhat unrecognizable.”

In 2009, the movie “2012”destroyed the world in the best special-effects fashion. The cable channel Spike TV has announced a new reality show called “Last Family on Earth,” in which one of the prizes is a spot in an underground bunker provided by Vivos, a company that sells space in such shelters. Vivos, for its part, maintains a countdown clock on its Website.

Striking a more positive note, the online stock trading firm Ameritrade suggests, “Say the sun rises on December 22, and you still need to retire. Ameritrade consultants can help you build a plan that suits your life.”

The end of days has been scheduled often during human history. The Bible’s Book of Revelation predicts it. Many Europeans expected the end of the world would come in the year 1000. More recently, American evangelist Harold Camping predicted doomsday would arrive May 21, 2011, then he switched the date to Oct. 21. Now he’s reconsidering.

The source of the current fear apparently is the end of the cycle of the Mayan Long Count calendar, one of the Mayans’ many calendars. The Mayan culture in Middle America thrived for six centuries before collapsing around 900 A.D., according to recent scholarship, because of a series of droughts and possibly warfare. The Mayans were sophisticated calendar makers and time keepers; in Guatemala recently, a Mayan mural with calendar calculations etched on the walls was discovered.

Kate Quinn, director of the University of Pennsylvania Museum of Archeology and Anthropology, or the Penn Museum, where the “Lords of Time” exhibit was displayed, says that the previous end date on the Mayan Long Count calendar occurred 5,125 years ago and was regarded as a significant event.

“They really thought of it as the turning over of dates, as the rebirth, the reawakening — the time to really reflect and start anew and just refresh,” Quinn said. “They really believed in that in the same way that we do with our New Year’s resolutions, but this was a bigger one for them. A much larger time frame. A very big party.”

Martin, co-curator of the exhibit, says that because of different correlations of dates, there is some dispute over when the Mayan Long Count calendar actually will end this time. He said you might want to wait until Dec. 25 to be in the clear.

In September 2011, Archeology Magazine published an article exploring various doomsday theories, from black holes to magnetic fields. Even the National Aeronautics and Space Administration is getting into the act, with its “Ask an Astrobiologist” feature including a question-and-answer column on “Nibiru and Doomsday 2012.” (Nibiru is a planet that the ancient Sumerians forecast would hit and destroy Earth.) E.C. Krupp of the Griffith Observatory in Los Angeles wrote an article for Sky and Telescope magazine going through various theories, “The Great 2012 Doomsday Scare.”

“In various spiritual and religious beliefs we find evidence of the end. It comes back as a kind of classic theme in the culture that we’re imagining it’s about to end,” says author Ben Winters, whose new mystery, “The Last Policeman,” is based on the premise of Earth’s destruction from an asteroid.

The doomsday theories provide “a reason to not be engaged in the world as it is,” he said. “To be thinking about some imagined future, some brutal future. It’s a kind of a fantasy, it’s a kind of escapism.”

Quinn said, however, that when the museum polled visitors to the Maya 2012 exhibit, most people were unaware of the details behind the Mayan Long calendar and the end of days.

“You ask, how do you think the world’s going to end, and they say, ‘Well, it’s something with the sun, aren’t we going to crash into something?’or, ‘It’s going to be a flood,’ and they didn’t really know,” Quinn said. “So there seemed to be a lot of theories out there, and a lot of opportunities out there for us to help the public to be directed to what we know to be true.”

Martin said that doomsday scenarios seem to be a North American phenomenon dating to the 1970s.

“It is something that recurs in societies that are looking for answers beyond what science seems to offer,” Martin said. “I think that people aren’t always happy with what science tells them.”

One positive benefit of the possible end of days, however, could be a boom for tourism in Honduras and other areas where Mayan civilization thrived.

“The hotels are selling out; the restaurants are going to be booked,” Quinn said. “It’s a great opportunity for them to bring in tourists altogether because the people who are interested in this idea of apocalyptic thinking, whether they believe the world going to end or not, they understand that the event is going to be here. They want to be there at that time.”

Locals in those areas seem bemused by it all, Quinn said. While preparing for the exhibit, she said, the descendants of the Mayans asked her, “Why do you Americans think the world’s going to end? And what is it with you people? How can you possibly trace it back to us?”