The end of the world is nigh, and the Web is alive with warnings presumably prophesied by the Mayan calendar.

Next Friday, at the winter solstice, planet Earth will go out with a bang, not a whimper — done in by a monster black hole, or some other unforeseen violence.

But it’s all nonsense perpetrated by a complete misreading of the Mayan calendar or the product of a hoax gone viral, say Mayan and planetary experts.

“It’s clear to me that most of the messages are based on what people are seeing on the Internet, and they’re seeing hoaxes,” said David Morrison, a planetary astronomer at the NASA Ames Research Center in Mountain View.

Rosalind Joyce , a professor of anthropology at UC Berkeley and a leading scholar on the ancient culture of Central America, has read the Mayan calendar texts inscribed on stone tablets, painted on ancient pottery and written on manuscripts now safely held in European libraries.

“The Maya never did predict the end of the world,” she said.

The Mayan calendar is confusing to many, she said. It counts long cycles of 144,000 days, with each cycle called a b’ak’tun, or baktun, and the Maya count back epochs over many cycles and then forward for thousands of years. “The ancient Maya had a concept of long, continuous time on their calendar, but never an ‘end time,’ “ Joyce said. “In their calendar this is now the 13th baktun, and it does end on Dec. 21 as the calendar says. But the cycle will then begin again as the 14th baktun, and there will always be another baktun.

“You can think of each cycle like a car’s odometer. When it comes to an end, you just reset it,” she said.

But whether a misreading of the calendar or a cruel prank, people are believing the end is at hand, and that can have tragic consequences, noted Morrison, who said his e-mail box is besieged this month with inquiries from frightened people.

“I call it cosmophobia,” he said. “A teacher in Stockton told me that the parents of two of her middle school students told her last summer that they were planning to kill themselves before the world ends on Dec. 21,” he recalled.

Among the predictions he is seeing for Friday: The Earth will be shattered by a wandering planet named Niburu, or by some other “Planet X”; the Earth’s rotation will suddenly reverse itself and all humanity will be destroyed; a black hole 30,000 light-years away will suck up the Earth and destroy it instantly; and three days of utter darkness will precede Christmas.

“There is no planet called Niburu,” Morrison said. “It was a minor god in ancient Mesopotamian writing, and in some books it’s just another fictional planet.”

As for Planet X, it’s just a term astronomers use for a hypothetical planet in our solar system -- as Pluto once was, and so was the dwarf planet now called Eris.

“Niburu and Planet X are the same thing, and neither one exists,” Morrison said. “If it were real, astronomers would have been tracking it, and by now it would be the brightest thing in the sky after the moon.

“And a black hole 30,000 light-years away? Nothing that far away could have any effect on Earth at all.”

As for the coming three days of darkness before the 21st?

“This crazy idea appeared about a week ago, but now many people are afraid of it,” Morrison said. “How do they think we could really have three days of darkness? Will the sun suddenly turn off for three days? It’s probably the silliest claim yet made about 2012.”

Robert Frost had it right when he wrote: “Some say the world will end in fire, some say in ice,” but that was a poem to warn that hate was the danger, not some ancient prophecy.