Cape Canaveral, Florida, Dec 21 - NASA is so sure there will be a December 22, 2012, it has already posted a YouTube video titled "Why the World Didn't End Yesterday."

Scientists say rumors on social media and the Internet of Earth's premature demise have been prompted by a misunderstanding of the ancient Maya calendar, which runs through December 21, 2012.

"It's just the end of the cycle and the beginning of the new one. It's just like on December 31, our calendar comes to an end, but a new calendar for the next year begins on January 1," Don Yeomans, head of NASA's Near-Earth Object program at the Jet Propulsion Laboratory in Pasadena, Calif., said in a separate YouTube video.

According to the story circulating on the Internet, an enormous rogue planet called Niburu is on a collision course with Earth.

"If it were, we would have seen it long ago and it if were invisible somehow, we would have seen its effects on the neighboring planets. Thousands of astronomers who scan the night skies on a daily basis have not seen this," Yeomans said.

Still, thousands of mystics and New Age dreamers have descended on ancient Maya temples across Mexico and Central America hoping to witness the birth of a new era when the day dubbed "end of the world" dawns on Friday.

So is NASA covering up to prevent panic?

"Can you imagine thousands of astronomers keeping the same secret from the public for several years?" Yeomans said.

Initially, Niburu, also known as Planet X, was to impact in May 2003, but when that didn't happen the doomsday date was moved to coincide with the end of one of the cycles of the ancient calendar at winter solstice -- December 21, 2012.

Other celestial events that will not be happening: a planetary alignment causing a massive tidal surge or a total blackout of Earth; a reversal in Earth's rotation; an impact by a giant asteroid; a giant solar storm.

"Since the beginning of recorded time, there have been literally hundreds of thousands of predictions for the end of the world," Yeomans said. "We're still here."

Mexico's Maya unmoved by end of earth hysteria

Izamal, Mexico, Dec 20 -Thousands of mystics, New Age dreamers and fans of pre-Hispanic culture have been drawn to Mexico in hopes of witnessing great things when the day in an old Maya calendar dubbed 'the end of the world' dawns on Friday.

But many of today's ethnic Maya cannot understand the fuss. Mostly Christian, they have looked on in wonder at the influx of foreign tourists to ancient cities in southern Mexico and Central America whose heyday passed hundreds of years ago.

For students of ancient Mesoamerican time-keeping, December 21, 2012 marks the end of a 5,125-year cycle in the Maya Long Calendar, an event one leading US scholar said in the 1960s could be interpreted as a kind of Armageddon for the Maya.

Academics and astronomers say too much weight was given to the words and have sought to allay fears the end is nigh.

But over the past few decades, fed by popular culture, Friday became seen by some western followers of alternative religions as a day on which momentous change could occur.

"It's a psychosis, a fad," said psychologist Vera Rodriguez, 29, a Mexican of Maya descent living in Izamal, Yucatan state, near the centre of the 2012 festivities, the site of Chichen Itza. "I think it's bad for our society and our culture."

Behind Rodriguez, her two children played in a living room decorated with Christmas trees and Santa Claus figurines.

Mexico's government forecast around 50 million tourists from home and abroad would visit southern Mexico in 2012. Up to 200,000 are expected to descend on Chichen Itza on Friday.

"It's a date for doing business, but for me it's just like any other day," said drinks vendor Julian Nohuicab, 34, an ethnic Maya working in the ruins of the ancient city of Coba in Quintana Roo state, not far from the beach resort of Cancun.

Watching busloads of white-haired pensioners and dreadlocked backpackers pile into their heartland, Maya old and young roll their eyes at the suggestion the world will end.

"We don't believe it," said Socorro Poot, 41, a housewife and mother of three in Holca, a village about 25 miles (40 km) from Chichen Itza. "Nobody knows the day and the hour. Only God knows."

Foreign Invaders

Tracing its origins to the end of the 4th millennium BC, the ancient Mesoamerican civilization of the Maya reached its peak between AD 250 and 900 when they ruled over large swathes of southern Mexico, Guatemala, Honduras and Belize.

Famed for developing hieroglyphic writing and an advanced astronomical system, the Maya then began a slow decline, but pockets of the civilization continued to flourish until they were finally subjugated by the Spanish in the 17th century.

Today, ethnic Maya are believed to number at least 7 million in Mexico, Guatemala and other parts of Central America.

The vast majority are nominally Roman Catholics, though many still uphold elements and rites of their old beliefs. According to a 2000 Mexican census, there were also a few hundred Jews and handful of Buddhists among the Maya.

Tales of human sacrifice, pioneering architectural feats and an interest in the stars burnished the Maya's supernatural reputation. So too, say experts, has the misguided notion that the Maya died out with the arrival of the conquistadors.

"That idea that they disappeared culturally back in the deep past is one of these things that feeds into this idea that they are mysterious, that they are otherworldly," said David Stuart, a Maya expert at the University of Texas.

The reality is that many Maya live in rural areas where water can be scarce, communications poor and education patchy.

Even as some shrug their shoulders at the awe and reverence December 21 has inspired, others worry it has become a free meal ticket for sharp-witted businessmen.

"There's the legend and there's the reality," said Yolanda Cornelio, 21, a tourism official in the city of Merida, whose mother speaks Maya at home. "Some people take the legend and abuse it, using it to make money. There's a lot of con artists."

With scores of old Maya ruins, temples and monuments dotting the landscape between southern Mexico and Central America, locals have plenty of opportunities to impress foreign visitors.

One of the most popular attractions lies in a leafy grove near the crumbling pyramids of Coba, where a large stone tablet records the Maya creation date of August 13, 3114 BC - quite literally the cornerstone of the 2012 phenomenon.

"This is a very powerful, sacred place," said Jonathan Ellerby, 39, a writer from Canada. "I feel something energetic, emotional, and I feel I'm in the right place. I really do."

Scientists in Hong Kong map initial anti-ageing formula

HONG KONG, Dec 20 - Scientists in Hong Kong appear to have mapped out a formula that can delay the ageing process in mice, a discovery they hope to replicate in people.

Their finding, published in the December issue of Cell Metabolism, builds on their work in 2005 which shed light on premature ageing, or progeria, a rare genetic disease that affects one in four million babies.

Progeria is obvious in the appearance of a child before it is a year old. Although their mental faculties are normal, they stop growing, lose body fat and suffer from wrinkled skin and hair loss. Like old people, they suffer stiff joints and a buildup of plaque in arteries which can lead to heart disease and stroke. Most die before they are 20 years old.

In that research, the team at the University of Hong Kong found that a mutation in the Lamin A protein, which lines the nucleus in human cells, disrupted the repair process in cells, thus resulting in accelerated aging.

Conversely, in their latest work using both mice and experiments in petri dishes, they found that normal and healthy Lamin A binds to and activates the gene SIRT1, which experts have long associated with longevity.

"We can develop drugs that mimic Lamin A or increase the binding between Lamin A and SIRT1," Liu Baohua, research assistant professor of biochemistry at the University of Hong Kong, told a news conference on Thursday.

The team went further to see if the binding efficiency between Lamin A and SIRTI would be boosted with resveratrol, a compound found in the skin of red grapes and other fruits which has been touted by some scientists and companies as a way to slow aging or remain healthy as people get older.

Associate professor Zhou Zhongjun, who led the study, said healthy mice fed with concentrated resveratrol fared significantly better than healthy mice not given the compound.

"We actually delayed the onset of ageing and extended the healthy lifespan," Zhou said of the mice.

Mice with progeria lived 30 percent longer when fed with resveratrol compared with progerial mice not given the compound.

Asked if their study supported the notion that drinking red wine delays ageing and reduces the risk of heart disease, Zhou said the alcohol content in wine would cause harm before any benefit could be derived.

"The amount of resveratrol in red wine is very low and it may not be beneficial. But the alcohol will cause damage to the body," Zhou said.

Hawking, CERN scoop richest science prize

London, Dec 11 -  Stephen Hawking, the British cosmologist who urged people to "be curious" in the Paralympics opening ceremony, has landed the richest prize in science for his work on quantum gravity and how black holes emit radiation.

Wheelchair-bound Hawking won $3 million from Russian Internet entrepreneur Yuri Milner, who set up his prize this year to address what he regards as a lack of recognition in the modern world for leading scientists.

Alongside Hawking, a second $3 million award has gone to the scientists behind the discovery this year of a new subatomic particle that behaves like the theoretical Higgs boson, imagined almost half a century ago and responsible for bestowing mass on other fundamental particles.

Diagnosed with motor neurone disease at the age of 21 and told in 1963 he had two years to live, Hawking, now 70, has become one of the world's most recognizable scientists after guest appearances on The Simpsons and on Star Trek.

At the opening ceremony of the Paralympic Games in London in August, speaking through his computerized voice system, he said: "Look up at the stars and not down at your feet. Be curious."

He was awarded the Special Fundamental Physics prize for what the committee called his "deep contributions to quantum gravity and quantum aspects of the early universe" as well has his discovery that black holes emit radiation.

"No one undertakes research in physics with the intention of winning a prize. It is the joy of discovering something no one knew before," Hawking said in comments emailed to Reuters.

"Nevertheless prizes like these prizes play an important role in giving public recognition for achievement in physics. They increase the stature of physics and interest in it."

Hawking said he planned to use the money to help his daughter with her autistic son and may also buy a holiday home - "not that I take many holidays because I the enjoy my work in theoretical physics".

HIGGS DISCOVERY

He shares the limelight with leaders of the project to build and run the Large Hadron Collider (LHC) particle accelerator at the CERN research centre near Geneva, which led to the discovery of a new particle that is thought to be the boson imagined by theorist Peter Higgs in 1964.

In the Standard Model, which governs scientific understanding of the basic make-up of the universe, the Higgs boson gives mass to other fundamental particles.

But in the half century before scientists at CERN started smashing particles together in the LHC and study the results, it sat in the realm of theory.

Although the work of building the LHC and running experiments in the particle accelerator involved thousands of scientists and engineers, the prize has been awarded to past and present team leaders.

The winners include the head of the LHC Lyn Evans, and the two spokespeople, Fabiola Gianotti and Joe Incandela, who presented the discovery to applause and cheers from the gathered physicists at CERN earlier this year.

Michel Della Negra, another prize-winner who for 15 years from 1990 led a team that built one of the two giant detectors used to find the Higgs at the LHC, told Reuters the award was a big surprise.

"For me it was totally unexpected," he said. "I didn't even know the prize existed."

Della Negra receives $250,000 because the $3 million is being split three ways between Evans, and the two teams working on the Atlas and CMS detectors. Two leaders of the Atlas team will get $500,000 each while the four from CMS get $250,000 apiece.

Although some of the recipients have pledged to put the money into projects to support science, singling out so few individuals from such a large project is sure to raise some eyebrows at CERN.