They both have seven neck vertebrae, as do all mammals except for manatees and sloths.

Because two-toed sloths have only six neck vertebrae, they find it hard to turn their heads.

Birds, who need to turn their heads a lot to preen, have many more neck vertebrae than mammals. Owls have fourteen; ducks, sixteen; but the record-holder is the mute swan with twenty-five.

Owls can't turn their head through 360, as some people claim, but they do manage 270. This is made possible by the extra vertebrae and specialised muscles that allow the bones to move independently of one another.

It compensates for the fact that owls can't move their eyes. If they want to change their view, they have to swivel their head.

An owl's eyes are forward-facing to increase their binocular vision, which is the ability to see things in three dimensions. This is essential for hunting at night. Their eyes are also very large to capture as much light as possible. If we had eyes on the same scale, they'd be the size of grapefruits.

Owls' eyes are tubular rather than spherical to create an even larger retina. A tawny owl's eyes are one hundred times more sensitive to light than ours. They can still see a mouse on the ground if the light level is reduced to a single candle 500 metres (about 547 yards) away.

How long have the Celts lived in Britain?

Since 21 June 1792.

It was then that a group of London 'bards' staged an entirely invented ceremony on Primrose Hill in London, involving a stone circle made from pebbles, and claimed they were reviving a ritual that stretched back to the ancient Celtic nation and its Druids.

Prior to this, there is no record of the word 'Celt' having been used to describe the pre-Roman inhabitants of Britain or Ireland and it was certainly never a term they used to describe themselves.

The word 'Celt' was coined by the Greek historian Herodotus in 450 BC BC when he described the peoples of the headwaters of the Danube north of the Alps. when he described the peoples of the headwaters of the Danube north of the Alps.

The Roman name for such people was Galli Galli ('chicken people') and they called the inhabitants of the British Isles ('chicken people') and they called the inhabitants of the British Isles Britanni Britanni, never Celts.

The use of the term 'Celt' in English dates from the seventeenth century.

A Welsh linguist living in Oxford called Edward Lluyd noted the similarities between the languages spoken in Ireland, Scotland, Wales, Cornwall and Brittany. He called these languages 'Celtic' and the name stuck. The word 'Celtic' has also been used to describe the curly-wurly style of design found in Irish gift-shops. There is no evidence to suggest that this was produced by an ethnically h.o.m.ogeneous group of people.

Most historians believe the language and culture we call 'Celtic' spread by contact not invasion. People 'became' Celtic by adopting the architecture, fashions and ways of speaking because they were useful or attractive, not because they belonged to the same ethnic group.

The romantic notion of a Celtic Empire of horse-loving master craftsmen, wise old Druids, harp-strumming poets, and fierce bearded warriors is the product of the Celtic Revival that started in the late eighteenth century.

It has more to do with modern Irish, Welsh and Scottish nationalism than with any historical reality.

Who was the first man to circ.u.mnavigate the globe?

Henry the Black.

An unfamiliar name to almost everyone, Enrique de Malaca was Magellan's slave and interpreter.

Ferdinand Magellan himself never completed his circ.u.mnavigation. He was killed in the Philippines in 1521, when he was only halfway round.

Magellan first visited the Far East in 1511, arriving from Portugal across the Indian Ocean. He found Henry the Black in a slave market in Malaysia in 1511 and took him back to Lisbon the way he had come.

Henry accompanied Magellan on all his subsequent voyages, including the round the world attempt which set off in 1519. This went in the other direction, across the Atlantic and the Pacific oceans, so when it arrived in the Far East in 1521, Henry became the first man to have been right round the world.

No one knows where Henry the Black was born he was probably captured and sold into slavery by Sumatran pirates as a child but when he arrived in the Philippines, he found the locals spoke his native language.

After Magellan's death, the expedition continued on its way, successfully completing the circ.u.mnavigation under Juan Sebastian Elcano, the Basque second-in-command.

Henry the Black was not with them. Elcano had refused to honour the promise made in Magellan's will to release Henry from slavery, so he escaped and was never seen again.

Juan Sebastian Elcano gets the credit for being the first man to travel round the world in a single trip.

He returned to Seville in September 1522. Five ships had set sail four years earlier but only the Victoria Victoria made it back. It was full of spices, but just eighteen of the original crew of 264 had survived: scurvy, malnutrition and skirmishes with indigenous peoples had accounted for the rest. made it back. It was full of spices, but just eighteen of the original crew of 264 had survived: scurvy, malnutrition and skirmishes with indigenous peoples had accounted for the rest.

The Spanish king awarded Elcano a coat of arms depicting the globe and carrying the motto 'You first circ.u.mnavigated me'.

Henry the Black is a national hero in several South-East Asian nations.

Who was the first to claim that the Earth goes round the Sun?

Aristarchus of Samos, born 310 BC BC, a whole 1,800 years before Copernicus.

Not only did Aristarchus suggest the Earth and planets travelled round the Sun, he also calculated the relative sizes and distances of the Earth, Moon and Sun and worked out that the heavens were not a celestial sphere, but a universe of almost infinite size. But no one paid much attention.

Aristarchus was most famous in his lifetime as a mathematician not an astronomer. We don't know much about him, except that he studied at the Lyceum at Alexandria and is later mentioned by the Roman architect Vitruvius as a man who was 'knowledgeable across all branches of science'. He also invented a hemispherical sundial.

Only one of his works has survived, On the Sizes and Distances of the Sun and Moon On the Sizes and Distances of the Sun and Moon. Unfortunately, it doesn't mention his sun-centred theory. The reason we know about it at all is due to a single remark in one of Archimedes' texts, which mentions Aristarchus' theories only to disagree with them.

Copernicus was certainly aware of Aristarchus because he credits him in the ma.n.u.script of his epoch-making On the On the Revolutions of the Heavenly Spheres Revolutions of the Heavenly Spheres. However, when the book was printed in 1514, all mentions of the visionary Greek had been removed, presumably by the publisher, nervous of it undermining the book's claims for originality.

Who invented the Theory of Relativity?

It wasn't Einstein. The theory of relativity was first stated by Galileo Galilei in his Dialogue concerning Dialogue concerning the World's Two Chief Systems the World's Two Chief Systems in 1632. in 1632.

To understand relativity we need to understand the theory that it replaced. This was the theory of 'absolute rest' postulated by Aristotle in the fourth century BC BC which stated that rest was the natural state of any object and that an object would return to this state if left to its own devices. which stated that rest was the natural state of any object and that an object would return to this state if left to its own devices.

The theory of relativity says that the motion of all objects is relative to the motion of each other, and that to define one as being 'at rest' is simply a matter of convention. It follows from this that the speed of an object cannot be stated absolutely only as 'relative' to something else.

Galileo, the Italian astronomer and philosopher, was also one of the founders of modern physics. He is most famous for his support of the 'Copernican' (or Aristarchan) theory, that the Earth went round the Sun.

The Catholic Church rounded smartly on him, but Galileo did not rot in a rat-infested cell for his principles. He began his sentence in the luxurious home of the Archbishop of Siena, before being taken back to a comfortable house arrest in his villa near Florence. It wasn't until 1992 that the Catholic Church finally admitted that Galileo's views on the solar system were correct.

While Galileo may have been right about this, he was perfectly capable of making mistakes: his favourite argument for a moving Earth was that this movement caused the tides. He observed that the Mediterranean is more tidal than the Red Sea, and attributed this to the water being sloshed about by the Earth's spin which he said acted more strongly on the Mediterranean because it is aligned East-West.

This argument was refuted by the eyewitness testimony of seafarers, who pointed out that there were two tides a day, not one as Galileo had a.s.sumed. Galileo refused to believe them.

Albert Einstein realised that Galileo had also made a mistake in his theory of relativity, or rather that the theory broke down in special circ.u.mstances.

Einstein's 1905 work, On the Electrodynamics of Moving Bodies On the Electrodynamics of Moving Bodies, was the first to talk about the Special Theory of Relativity, which describes the strange properties of particles moving at close to the speed of light in a vacuum.

The General Theory of Relativity, which applied the special theory to large-scale phenomena like gravity, was published ten years later in 1915.

What shape did Columbus think the Earth was?

a) Flat b) Round c) Pear-shaped d) An oblate spheroid Columbus himself never said the world was round he thought it was pear-shaped and about a quarter of its actual size.

Despite his later reputation, his voyage of 1492 wasn't intended to discover a new continent but to prove that Asia was much closer than anyone imagined. He was wrong.

Columbus never actually set foot on mainland America the closest he came was the Bahamas (probably the small island of Plana Cays) but made his crew swear an oath that, if asked, they would say they'd reached India. He died in Valladolid in 1506 and remained convinced to the end that he'd reached the coast of Asia.

There is a remarkable degree of uncertainty about Columbus. Most of the evidence points to him being the son of a Genoese weaver called Domenico Columbo, but there are enough inconsistencies for him to be claimed as Sephardic Jewish, Spanish, Corsican, Portuguese, Catalan or even Greek.

He spoke the Genovese dialect (not Italian) as his first tongue and learnt to read and write in Spanish (with a marked Portuguese accent) and Latin. He even wrote a secret diary in Greek.

We don't know what he looked like, as no authentic portrait survives, but his son claimed he was blond until the age of thirty, whereupon his hair turned completely white.

We don't even know where he is buried. We do know his corpse had its flesh removed, as was the style for the great and the good in the sixteenth century, and that his bones were interred first in Valladolid, then in the Carthusian monastery in Seville, then in Santa Domingo, Cuba, then Havana, then, and apparently finally, in Seville Cathedral in 1898.

However, a casket with his name on remains in Santa Domingo and now Genoa and Pavia have also made competing claims to hold bits of him. DNA tests are under way, but it seems likely that the final resting place of Columbus or Columbo, or Colon (as he preferred) will remain as contentious as the rest of his life and achievements.

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What shape did medieval people think the Earth was?

Not what you think.

Since around the fourth century BC BC, almost no one, anywhere, has believed that the earth is flat. However, if you did want to show the earth as a flat disc, you'd end up with something very similar to the United Nations flag.

Belief in a flat Earth may not even have actually originated until the nineteenth century. The guilty text was Washington Irving's semi-fictional The Life and Voyages of Christopher Columbus The Life and Voyages of Christopher Columbus (1828) which, incorrectly, suggests that Columbus's voyage was made to prove the world was round. (1828) which, incorrectly, suggests that Columbus's voyage was made to prove the world was round.

The idea of a flat earth was first seriously put forward in 1838 by the eccentric Englishman Samuel Birley Rowbotham who published a sixteen-page paper ent.i.tled: 'Zetetic Astronomy: A Description of Several Experiments which Prove that the Surface of the Sea Is a Perfect Plane and that the Earth Is Not a Globe' ('Zetetic' derives from the Greek zetein zetein, meaning 'to search, or inquire').

More than a century later, a member of the Royal Astronomical Society and devout Christian called Samuel Shenton re-branded the Universal Zetetic Society as the International Flat Earth Society.

The NASA s.p.a.ce programme of the 1960s, culminating in the lunar landings, should have buried the issue. But Shenton was undeterred. Looking at photographs of a spherical earth taken from s.p.a.ce, he commented: 'It's easy to see how a photograph like that could fool the untrained eye.' The Apollo landings were, apparently, a Hollywood hoax, scripted by Arthur C. Clarke. Membership shot up.

Shenton died in 1971 but not before choosing his successor as President of the Society. The odd but charismatic Charles K. Johnson took over and made the Society a rallying point for a heroic, homespun 'anti-Big Science' movement. By the early 1990s, membership had surged to over 3,500.

Johnson, who lived and worked in the vast flatness of the Mojave desert, proposed a world in which we live on a disc, with the North Pole at its centre, surrounded by a 150-foot-high perimeter wall of ice. The sun and moon are both 32 miles in diameter, and the stars are 'about as far away as San Francisco is from Boston'.

Johnson's desert hideaway burnt down in 1995, destroying all the Society's archives and membership lists. Johnson died in 2001, by which time the Society had shrunk to a few hundred members. It exists today solely as a web forum, www.theflatearthsociety.org, with around 800 registered users.

ALAN Are all the stars round? Are all the stars round?

STEPHEN I can't answer that. Erm ... I think, probably, most of them I can't answer that. Erm ... I think, probably, most of them ALAN [doubtfully] And yet you know what people thought 500 years ago. [doubtfully] And yet you know what people thought 500 years ago.

STEPHEN Can I read books? Yes. Have I visited every star in the universe? No. Is that something that you find difficult to understand? Can I read books? Yes. Have I visited every star in the universe? No. Is that something that you find difficult to understand?

Who first discovered that the world was round?

Not who, what. Bees worked it out first.

Honeybees have evolved a complex language to tell each other where the best nectar is, using the sun as a reference point. Amazingly, they can also do this on overcast days and at night, by calculating the position of the sun on the other side of the world on the other side of the world. This means they can actually learn and store information, despite having a brain 1.5 million times smaller than our own.

A bee's brain has about 950,000 neurons. A human brain has between 100 and 200 billion.

Honeybees have an in-built 'map' of the sun's movements across the sky over twenty-four hours and can modify this map to fit local conditions very quickly all decisions about where to fly are made within five seconds.

The honeybee is also more sensitive to the Earth's magnetic field than any other creature. They use this for navigation and for making the honeycomb panels of their hives. If a strong magnet is put next to a hive under construction, a strange cylindrical comb results, unlike anything found in nature.

The temperature of a beehive is the same as that of a human body.

Bees evolved about 150 million years ago in the Cretaceous period, roughly at the same time as flowering plants. The honeybee family, Apis Apis, didn't appear until 25 million years ago. They are really a form of vegetarian wasp.

Bees smell with their antennae. Queen honeybees give off a chemical called 'queen-substance' which prevents worker bees developing ovaries.

It takes the entire lifetimes of twelve bees to make enough honey to fill a teaspoon. Bees will travel as much as 12 km (7.5 miles) per trip, several times a day. A single bee would have to travel about 75,000 km (46,600 miles) to make a pound of honey (or less than half a kilo), which is almost twice round the world.

Why do bees buzz?

To communicate.

Bees use their buzzing much as they use their movements, or 'dancing': to pa.s.s on information. Ten distinct sounds have been identified and some have been linked to specific activities.

The most obvious of these uses is 'fanning' to cool the hive. It is loud and steady at about 250 beats per second, and is amplified by the hive itself. Bees also buzz more loudly to signal danger (anyone who has approached a hive will have noticed the change in tone) followed by a sequence of 500 beats per second pulses to sound the 'all clear' and calm the hive.

The queen bee has a particularly rich range of sounds. When a new queen hatches she makes a high-pitched chirrup called 'piping' or 'tooting'. Her sisters (still curled up inside their cells) answer with a croak-like call called 'quarking'. This is a big mistake: there can only be one queen. Using the 'quarks' as a guide, the hatched queen picks each off in turn, tearing open their cells and either stinging them to death or ripping their heads off.

Bees use their legs to hear: sound 'messages' in the hive are communicated through the intensity of the vibration. However, recent research into bees' antennae suggest that as well as the chemical receptors they use to 'smell', the antennae are covered in eardrum-like plates, which might be 'ears'.

This would explain why other workers touch the dancing bee's thorax with their antennae rather than the 'waggling' abdomen during the 'waggle dance' they are hearing the directions to the nectar rather than seeing them. After all, it's dark in a hive.

How bees buzz is more controversial. Until recently, the main theory was that they used the fourteen breathing holes along their sides (called 'spiracles') rather as a trumpeter controls the sound of his instrument with his lips.

Entomologists at the University of California have ruled out this theory by carefully blocking the spiracles. The bees still buzzed.

The latest hypothesis is that buzzing is partly caused by the vibration of the wings, with some amplification from the thorax. Clipping a bee's wings doesn't stop the buzzing, though it does change its timbre and intensity.