A HIT OR MYTH? New book establishes whether commonly held 'truths' are wrong.

Byline: By Craig McQueen

WE all know Everest is the world's biggest mountain and carrots help you see in the dark.Or do we?

Not according to a new book, which sets out to debunk common myths we've been accepting as fact since childhood.

Actually Factually contains the truth behind dozens of beliefs we take for granted, covering everything from science to geography to history.

So if you want to be armed with the right knowledge the next time someone tells you the Sahara is the world's biggest desert, read on...

CHRISTOPHER COLUMBUS DISCOVERED AMERICA

Columbus was not the first man to reach the USA. Native American tribes were there more than 10,000 years earlier, and are thought to have arrived on the continent from Siberia.

Columbus didn't even set foot in the USA. He is believed to have landed in the Bahamas, and mistakenly thought he'd reached India. That's why he called the locals "Indians".

Even if he had reached America, he wouldn't have been the first European, as the Vikings had set up colonies in Greenland and Canada 400 years before he was born.

THERE ARE MORE PEOPLE ON EARTH NOW THAN HAVE EVER LIVED

It is thought humans have been around for the last 50,000 years, and to estimate how many people have lived and died in that time, you need to look at birth rates and life expectancy, which change a lot through living conditions, natural disasters and disease.

The Population Reference Bureau in Washington DC estimate that more than 105billion people have lived and died in the last 10,000 years. The current population has only reached 6.6billion, so it's very unlikely to reach 105billion any time soon.

MOUNT EVEREST IS HIGHEST MOUNTAIN IN THE WORLD

This title can be awarded in a number of different ways. At 29,028ft, Everest is the highest point above sea level, but it isn't the tallest mountain.

From base to peak, the tallest is Mauna Kea in Hawaii, measuring 33,476ft. The difference is, only 13,803ft of it is above the surface of the ocean.

If you're looking for the point furthest from the centre of the Earth, Mount Chimborazo in Ecuador is the winner. It's only 20,703ft, but it's near the equator and the Earth bulges in the middle.

LEMMINGS JUMP OFF CLIFFS

This sad event was "captured" in the 1958 Disney film White Wilderness. It was filmed in Alberta, Canada, where Lemmings aren't normally found.

Further investigation revealed the film crew had brought in a couple of crates of lemmings, made them run about for the cameras and then herded them over the edge of a cliff to provide an emotional end to the film.

This led some people to think lemmings do this as a form of population control. While lemmings do leave their colonies in search of food when they are overcrowded, they don't kill themselves on purpose.

HEINZ HAS 57 VARIETIES

Henry John Heinz started selling his bottled pickles and vegetables in 1869, and to draw attention to his products, he started putting massive "pickles" adverts all over America. He became a huge success.

In 1892, he spotted a poster for a shoe company advertising 21 different styles.

The precise number appealed to him and, although at the time he was already selling more than 57 varieties of products, he and his wife felt the numbers five and seven were lucky, so he chose 57 and stuck with it.

THE SAHARA IS THE WORLD'S LARGEST DESERT

A "desert" is any area of land that receives less that 250millilitres of rain in a year. About a third of the Earth's land qualifies under this rule, including the Sahara.

And as the Sahara covers one third of Africa, with about the same land mass as the USA, you'd think that it would be the biggest at more than 5.3million square miles.

But it's only the third biggest, behind Antarctica, with more than 11.1million square miles in winter, and the Arctic, with more than 9.3million square miles in winter.

We may not think of these icy wastelands as desert, but they still qualify due to low rainfall, even though the Arctic is then a desert and an ocean at the same time.

RING A RING O' ROSES IS ABOUT THE BLACK DEATH

The Black Death was the name given to the bubonic plague which swept through Europe from 1347 to 1353, yet the earliest record of the rhyme was in a book published in 1881.

Nursery rhymes were a popular subject for books many years before 1881, and it seems unlikely no one had recorded this one in 500 years.

And it wasn't until the 1960s that someone suggested the rhyme could be about the Black Death. It seemed so deliciously gruesome that it's been accepted as fact ever since.

CARROTS HELP YOU SEE IN THE DARK

Carrots contain a lot of vitamin A, which is essential for healthy eyes, but it doesn't make your vision any better or help you see in the dark.

The reason people think carrots can do this is due to a cover story put out by the RAF during the war. When the number of Luftwaffe planes being shot down suddenly increased, they said pilots were on high-carrot diets to improve their night vision.

In fact, the success was due to a new radar system which located planes from much further away. The carrot story was constructed to throw the enemy off the scent.

A GOLDFISH HAS A MEMORY OF ABOUT THREE SECONDS

The goldfish "fact" makes you feel better about keeping it in a bowl with just some coloured gravel and a plastic castle for company.

But, in fact, goldfish are smarter than you think.

In scientific tests, goldfish have learned to swim through mazes and perform the odd trick for food.

They have been able to remember how to repeat what they did up to 11 months later, which is the equivalent of a human remembering something for more than 40 years.

PIRATES MADE PEOPLE WALK THE PLANK

While sailing was a dangerous job and losing the odd leg or eye may have been common, much of the image we have of pirates comes from story writers and Hollywood rather than history.

They didn't kill people very often as poorly paid sailors usually surrendered, and there is no record of pirates ever making people walk the plank.

The legend may go back to the Roman historian Plutarch, who wrote of pirates boarding ships, singling out any Romans and granting them freedom - by letting them climb down the ship's ladder into the open sea.

Actually Factually by Guy Campbell is published on Thursday by Buster Books, priced pounds 7.99.

'The Sahara is only the third biggest desert. Antarctica is the largest'

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HIGH POINT: Mount Everest PICTURE: REUTERS