Tabla de contenidos para You: Did you know? 2019 en You: Did you know?

ALL elephants may look alike, but they are actually divided into two main categories: the African and Asian elephants. The African elephant is bigger than the Asian elephant and has larger ears and less hair on its body. The elephant is often seen as an aggressive animal, but it’s actually a gentle giant and deeply emotional being. It’s the only creature, other than humans, to grieve for its dead and blows its trumpet and cries when upset. The African elephant is the largest mammal on land and lives until it’s about 70 years old, around the same age as the average human. It’s one of the Big Five, along with the lion, rhino, leopard and buffalo. WHERE IS IT FOUND? There are two types of African elephants. The African bush…

SPIDER WASPS The tarantula hawk wasp is a spider wasp from the same family as bees, ants and other wasps. This wasp is ferocious and hunts spiders often larger than itself. It doesn’t eat the spiders (it eats nectar and plants) but uses them as incubators and food for its larva. There are 4 200 spider wasp species worldwide. Tarantula hawk wasps are found in North and South America, Africa, Southeast Asia and Australia. REPRODUCTION This solitary wasp mates only once in its lifetime. Females are produced from fertilised eggs and males from unfertilised ones, so after mating the female stores the sperm for when she wants to fertilise an egg to produce a female wasp. When she’s ready to lay an egg the female hunts for a tarantula spider.…

THE dragonfly starts its life in water so it’s often found near ponds, lakes, canals, streams, rivers and wetlands. About 6 000 species of dragonfly and damselfly – both belong to the insect sub-group Odonata – are known but scientists say there could be many more. An adult dragonfly lives for about two months. EYES Compared to other insects, dragonfly vision is extraordinarily good. The head consists almost entirely of two huge compound eyes – each eye has a mesh-like appearance because it contains as many as 30 000 ommatidia (lenses). A dragonfly uses about 80% of its brain to process all this visual information. They can see many more colours than humans. IT HAS NEARLY 360° vision This remarkable vision helps it detect the movement of other insects and…

ONE of the most famous fynbos plants is the spectacular king protea, which has been South Africa’s national flower since 1976. It has the largest flower head in the protea family, which explains its name. But the king protea is only one of more than 1 000 varieties of protea, which come in many shapes and sizes. One of the things that makes the king protea so fascinating is that it’s technically not one flower but an inflorescence (flower head) made up of hundreds of individual flowers grouped together. What appear to be the petals are actually a type of leaf known as floral or involucral bracts. GIVE AND TAKE Nectarivorous birds (birds that feed on nectar) such as sunbirds and sugarbirds love to drink the protea’s sweet syrup. To…

PHOTOSYNTHESIS is the clever process whereby plants make their own food and, as a vital bonus, the oxygen (O2) we need to survive. Plants have an important relationship with animals and humans – we inhale the O2 they exhale, and they inhale the carbon dioxide (CO2) we exhale. THE FORMULA Light energy is used to convert carbon dioxide and water into food. Oxygen is released as a by-product. CO2 H2O SUNLIGHT + + + CHLOROPHYLL This is how photosynthesis works: 1. The sun shines on a plant. 2. A substance called chlorophyll (which is what makes a plant green and is usually found in its leaves) absorbs the sun’s energy and stores it. 3. The plant uses this stored energy to break down water (which it sucks in through its…

HE Pyramids of Giza are probably the most famous landmark in Egypt, but they’re not the Ancient Egyptians’ only incredible feat of engineering. There are also the two temples at Abu Simbel, built by Pharaoh Ramses II in 1244 BC. And in the 1960s this world heritage site was moved from its original spot! INSIDE THE GREAT TEMPLE THE GREAT HALL Four enormous statues of Ramses wearing the double crown of Upper and Lower Egypt flank the Great Temple’s entrance. Smaller statues depict his favourite wife, Nefertari, his mother, Tuya, his two eldest sons and six eldest daughters. THE HYPOSTYLE HALL The main hall is supported by eight huge pillars that show Ramses as the god of the underworld, Osiris. Floor-to-ceiling murals depict Ramses’ battles. THE SANCTUARY Only the pharaoh…

ITTOOK nearly six years to build this beautiful basilica (church) in Istanbul, Turkey. It was completed in the year 537. From about 660 BC Istanbul was known as Byzantium and from 330 as Constantinople. It was given the name Istanbul after the Turkish conquest of the region in 1453. The basilica was at first a Greek Orthodox cathedral, later a mosque and is now a museum. It became a world heritage site in 1985 and is a popular tourist spot in Turkey. HISTORY LOCATION Istanbul, Turkey. CONSTRUCTED It was built under Justinian, who ruled the Eastern Roman Empire from 527 to 565. The architects were Isidore and Anthemius. ARCHITECTURAL STYLE The building is seen as one of the best examples of Byzantine architecture (architecture of the Byzantine Empire which was…

TODAY postimpressionist painter Vincent van Gogh (1853-1890) is regarded as the greatest Dutch artist since Rembrandt and one of the most important figures in the history of Western art. It’s sad to think that he was overwhelmed with failure and rejection during his life and his work started attracting attention only in the year after his death. Today his works are among the world’s most expensive paintings. His most famous, Starry Night (1889), hangs in New York’s Museum of Modern Art. He died in July 1890, of a gunshot wound to his stomach. It’s not clear who shot him. He was 37. He spoke Dutch, French, German and English. His brother Theo named his son after him. He never married, had no children and named Theo his heir. Of his…

THE Cullinan diamond, the largest whole diamond discovered to date, was found at the Premier mine in Cullinan near Pretoria, in 1905. It weighed a whopping 3 106 carats – that’s 621,2g – heavier than a soccer ball. The gem was given to King Edward VII of Britain in 1907 for his 66th birthday. It was later cut up into nine major stones, including the Great Star of Africa. These are now in either the British crown jewels – a collection of ceremonial items – or the personal possession of the British royal family. WHY THE NAME CULLINAN? The stone was named after Sir Thomas Cullinan, owner of the Premier diamond mine. The mine has uncovered some of the world’s largest diamonds and is the third-richest diamond-producing mine in South…

SCIENTISTS believe the moon was once part of Earth – they theorise that a large object collided with Earth about four billion years ago and broke off large rocks that eventually melted together to form the moon. It is also Earth’s only natural satellite (a satellite is any celestial body in space that orbits around a larger body, in this case it’s Earth). Gravity on the moon is about a sixth of Earth’s so astronauts who have been to the moon had to wear special gear to prevent them floating off into space. That’s why you’ll weigh about six times less on the moon than on Earth! There’s now renewed interest in visiting the moon again. A number of countries and private companies have indicated they would like to travel…

SOME years ago Lottie Williams was on a late-night walk in the American state of Oklahoma when she saw a streak of light in the sky, then felt something drop on her shoulder. It turned out to be a small chunk from a rocket that had fallen from space. Luckily Lottie wasn’t hurt – and just as fortunately this remains the only known case of a person being hit by a piece of space junk. In the more than 60 years that humans have been sending stuff into space, we have left so much debris (pieces of rubbish) up there that it may be putting us all in danger. Space debris not only falls to Earth – it can also collide with a spacewalking astronaut or a working satellite. The…

YOU’VE probably seen a weather presenter at the end of a news programme on TV standing in front of a map and talking about wind speeds in various parts of the country. An anemometer (wind meter or wind gauge) is the instrument meteorologists (scientists who study the weather) use to measure the speed of wind. The name comes from the Greek word “anemos”, which means “wind”. Let’s take a look at how you can build your own wind meter to measure how fast the wind is blowing. CUP OF A DIFFERENT COLOUR You need this to prepare your anemometer and measure the speed of the wind. WHATYOU WILL NEED CHECKING YOUR WIND METER STEP 1 On a windless day have an adult drive you down the street at 10km/h. Hold…

DID YOU KNOW? THIS is our third edition of YOU Did Know? and every issue reminds me just how much we don’t know about the fascinating world around us and how wonderful it is to learn something new. And the great thing about curious kids who want to know more about the world, is as we try to answer the many questions they bombard us with we are learning too. My seven-year-old daughter is currently obsessed with animals so we regularly watch shows about all sorts of creatures or read about them. There are so many interesting facts that the whole family picks up. I know she is going to love the latest issue of YOU Did You Know? as we have a bumper animal section divided into Big Creatures…

THE LION is the second biggest member of the cat family; only the tiger is bigger. But, in the realm of stories, fables and legends, the lion still wears the crown of king of the jungle. It is also one of the Big Five along with the rhino, elephant, leopard and buffalo. Most lions are found in the area south of the Sahara in Africa, but a small population is also found in a forested area in Asia. The Asiatic lion is smaller than its African cousin. Here we look at the African lion. WHERE DOES IT LIVE IN AFRICA? The African lion is found in the wild in South Africa, Angola, Botswana, Mozambique, Tanzania, South Sudan and other parts of Central Africa south of the Sahara desert. HOW BIG…

SNAKES are either venomous or non-venomous. Those with venom bite their prey to paralyse or kill them, but non-venomous ones, like the green anaconda, use constriction. The anaconda wraps its body around its prey. It squeezes hard enough to kill and swallows its prey whole. It eats large animals such as pigs, deer and even big cats, but how can it fit a big creature into its mouth and stomach? Let’s find out. WHERE DOES IT LIVE? ● The green anaconda lives in the tropical rainforests of South America. ● The scientific name for the green anaconda is Eunectes murinus. Eunectes means “good swimmer” in Greek and murinus means “of mice” in Latin, referring to one of the things the snakes eat. ● It moves awkwardly on land, but the…

HE chameleon (the name means earth lion in Greek) is a member of the reptile family and remarkable for so many reasons, most of all because it can change colour in just a few moments. There are about 160 species of chameleon and most are found in sub-Saharan Africa and Madagascar. CHANGE OF COLOUR The chameleon changes colour by adjusting special crystals in its cells to reflect different shades of colour. Some can change to all the colours of the rainbow as well as pink, black and brown. Colour changes are a function of mating and can be a reaction to its mood and the temperature. It becomes brighter when showing aggression to other chameleons during a fight. The colour changes also help to camouflage it from predators such as…

A NIMALS are not the only ones that hunt and devour prey – some plants do too! The plants get some of their nutrients by digesting insects. They use a few ways to trap insects such as the pitcher method and flypaper method. In the pitcher method, insects land on a jug-shaped plant, slide on the slippery rim and fall inside. The Venus flytrap, native to North and South Carolina in America but found across the world due to people’s fascination with this plant, uses the flypaper method. This is how it works. CILIA These hard protrusions fold together to help prevent prey from escaping. A STICKY SITUATION The inside of the leaf lobes secretes (gives off) a sticky substance (mucilage), which helps trap prey. LEAF LOBE Each leaf has…

THE sunflower comes from North and Central America and there are about 70 sunflower species. Not all sunflowers are yellow, some are brown, orange, red and even purple. Spanish explorers brought sunflowers from Mexico to Europe in the 1500s but the plant dates back to about 3000 BC when Native Americans began domesticating and breeding it to produce a single head with a variety of coloured seeds. Today sunflowers are an important food crop in many parts of the world. In South Africa, they’re grown mainly in Limpopo, Mpumalanga, North West and Free State. It’s the national flower of the Ukraine which was also the world’s top producer of sunflowers in 2017/18. The oil extracted from sunflower seeds is used to make cooking oil and margarine. The seeds also make…

ABOUT 70% of Earth is covered in water, but it doesn’t stay in one place – water is continually distributed all over our planet. All water moves continously in a gigantic cycle known as the water or hydrologic cycle. In this cycle water evaporates from water masses and ground on the surface of Earth, rises into the atmosphere, cools and condenses to form clouds. It then falls again to Earth as precipitation (eg, rain, hail or snow). WHAT IS TRANSPIRATION? This is the process by which water is carried through plants (including trees), from their roots to small pores (stomata) on the undersides of leaves, where it becomes vapour and is released into the atmosphere. WHAT IS CONDENSATION? This is when water vapour in the air cools down and changes…

FOSSILS are rare – for every animal that dies the chances are one in a million it will become a fossil meaning it will be preserved instead of decaying. For a fossil to form successfully a number of things must happen in the correct order. If just one step is left out, the remains of the prehistoric plant or animal won’t survive to be discovered by scientists centuries later. A fossil forms when minerals such as calcium carbonate replace the bones or other organic material from an animal or plant and it petrifies, this means the minerals convert it into a hardened preserved state. It can now survive for thousands or even millions of years, during which the fossil is continually covered with new layers of stone and sand. Erosion…

THIS amazing building was built more than 800 years ago (between 1200 and 1330) in Djenné on the flood plains of the Bani River in Mali in Africa. It isn’t built using the usual bricks and mortar, but mud. This world heritage site was first used as a palace, before it was eventually turned into a mosque. The mosque was rebuilt by the French in 1907 after falling into disrepair. TOMB The remains of Almany Ismaila, an important imam of the 18th century, are kept in this tomb. WALLS Made of sun-baked earth bricks (called ferey), and sand-and earth-based mortar, the walls are coated with a plaster, which gives the building its smooth, sculpted look. THE PRAYER WALL The prayer wall or qibla faces east towards Mecca (a holy city…

MANY people think the most valuable material on Earth is gold. And, yes, it’s in the top 15 but there are quite a few others that are more expensive and some of them you might not even have heard of. These are so expensive because they are rare and are difficult to make or mine. We have added the price tag of each substance, with values given per gram. $4 500 (R63 000) DIAMONDS Even though they aren’t the rarest gems, diamonds are the most expensive because they’re much sought-after for engagement rings and other jewellery. They’re formed deep under Earth’s crust through intense pressure and heat, which transforms carbon molecules into the world’s hardest naturally occurring substance. Because diamonds are so strong, the car, mining, military and other industries…

NEXT to Earth, Mars is the planet in our solar system that’s most habitable for humans. With Earth’s resources dwindling and its population expanding, colonising Mars could help humankind survive. Let’s take a look at what life on the Red Planet would require. FOOD Colonisers will need to grow fruit and vegetables to eat. As Mars’ atmosphere is 95% carbon dioxide and its soil doesn’t have enough nutrients, plants would need to be grown in special pressurised greenhouses that would also protect them against extremely cold temperatures and violent dust storms. Fortunately there’s enough sunlight. PRESSURISED SUITS In order to survive despite the lack of oxygen, low air pressure and icy cold temperatures, humans would need to wear special spacesuits whenever they went outside (see page 82). WATER Humans need…

IT’S A model that dates far back to the Roman Empire. In 30 AD doctors told Emperor Tiberius it was necessary for his health to eat Armenian cucumbers all year, even though the fruit grew only in summer. So his gardeners created an enclosed structure to provide protection for growing plants. In winter, fires were lit outside the stone walls of the structure to keep the inside heated. The roof was made of a thin material called mica, which allowed sunshine in. This was the world’s first greenhouse. Today, greenhouses are usually made from glass or special plastic to allow sunlight through. The heat caused by solar radiation from the sun is kept from leaving the greenhouse through convection, so the structure stays heated even on cold days. This creates…

CLINGFILM The taped-down plastic clingfilm provides insulation so the heat can’t escape. The plastic has to be transparent so the light can get through. NEWSPAPER The newspaper insulates the oven so it keeps in more heat. Roll up the sheets of newspaper tightly and tape them inside so they form a border around the cooking area (the black paper). The lid should still be able to close so the heat can’t escape. HOW HOT DOES IT GET? Your solar oven will reach almost 100°C on a hot day and will take 45-60 minutes to make the s’mores, depending on how hot it is. The best hours to set up the oven are when the sun is high overhead. ALUMINIUM FOIL The foil is reflective and concentrates the sun’s rays down…

THERE are thousands of different types of snails in the world. Some are found in the sea, others in freshwater lakes and rivers, some on land in the wild, and some are found in your garden. The garden snail is the one we are all familiar with and will take a closer look at here. There are also edible snails (served in a dish called escargot) but you can’t eat the ones in your garden. If you spot a snail that doesn’t have a shell, it’s not a snail it’s a slug. OPERCULUM Most snails have a hard lid called the operculum. Some snails use it to seal themselves into their shells for protection. Once inside the shell the snail’s body stays moist. The snail has an open blood system.…

IAIZE, or mealies, is an important food source in South Africa and one of our key crops. South Africans eat a lot of mealies – either whole or ground as mealie meal – so it’s regarded as one of our staple foods. Staples are foods grown and eaten in large quantities by a particular nation or population group. They are quite cheap, readily available and nutritious. Maize, a type of corn, was first grown in Mexico. It then spread across North and South America. After European explorers landed in the Americas in the late 15th and early 16th century, maize was grown around the world. Because maize needs a lot of sun, the only continent where it’s not grown is Antarctica. Mealie comes from the Afrikaans word “mielie”, which originates…

THIS natural disaster is a series of gigantic waves that are usually generated after an earthquake, landslide or volcanic eruption in an ocean. This can have disastrous results when the waves reach a shore. The Boxing Day tsunami on 26 December 2004 killed more than 200 000 people when it struck countries in the Ring of Fire (see right) in the Pacific Ocean. In March 2011 thousands died after an earthquake and tsunami hit Japan and in October 2018 a tsunami hit Indonesia killing hundreds of people. Waves are often higher than 30M A tsunami’s first wave isn’t necessarily the biggest. They can gradually get bigger. Waves can travel at speeds of up to 800KM/H – nearly as fast as a jet airliner! HOW DOES A TSUNAMI OCCUR? Large earthquakes occur…

TIME zones usually follow meridians (imaginary lines from pole to pole), which are “moved” in some places to enable whole countries to fit into a single time zone. There are supposed to be 24 time zones of 15 degrees of longitude each, one hour apart. In reality there are 40 time zones because many countries use half-hour zones. Australia has an extra, unofficial time zone. South African time is indicated as GMT+2 to show we’re two hours ahead of Greenwich Mean Time, which is at O degrees longitude. Some countries prefer to say UTC+2, which means Coordinated Universal Time. RUSSIA Russia used to have 11 time zones – the most in the world – but they reduced it to “only” nine in 2010. CHINA China stretches over five time zones…

HE Great Wall of China is actually a series of walls and fortifications. The first walls were built by independent kingdoms to defend their borders. These were later joined under Qin Shi Huang, the first emperor of a unified China, to drive back attacks from northern tribes. The most impressive and best-preserved sections of the wall were built by the Ming Dynasty. Large parts of the wall have been destroyed or eroded. WHO BUILT THE WALL? The Spring and Autumn Period and the Warring States Period (770-221 BC) The oldest existing part of the wall is built by the ruler of the Qi kingdom. The Qin Dynasty (221-207 BC) Emperor Qin Shi Huang orders the walls to be connected to protect his new empire. The Han Dynasty (207-220 AD) Han…

HE’S best known for his art, including two of the most famous paintings in the world, but Italian Leonardo daVinci (1452-1519) was also successful in other areas and had a wide range of interests. In this way he can be seen as a true “Renaissance man”. Da Vinci was fascinated by the world around him and how things worked. He used his artistic abilities to record what he saw and filled dozens of notebooks with drawings of bodies, buildings and natural processes such as the flow of water and the flight of birds. His scientific knowledge made his art lifelike, and inspired him to invent machines that were way ahead of their time. WHAT WAS THE RENAISSANCE? “Renaissance” means “rebirth” in French and refers to a time in Europe 800…

MY COUNTRY, MY CLOTH Gandhi spent time every day spinning yarn on his charkha (spinning wheel), a message to other Indians to value manual labour and self-reliance. CLOTHING Gandhi wore a lungi (a long piece of cotton cloth). Later he started wearing a dhoti (a long skirt) and a turban. A SIMPLE LIFE Gandhi owned only essential items such as his spectacles, pocket watch and sandals. EVENTS IN THE LIFE OF GANDHI 1869 Mohandas Karamch and Gandhi is born on 2 October in India to a wealthy Hindu family. 1883 Thirteen-year old Gandhi marries Kasturba Makhanji, also 13, in an arranged marriage. They go on to have four sons. 1888 Against his family’s wishes, Gandhi travels to London to study law. 1893 Unable to find a job in India after…

SA has the deepest gold mines in the world and the third-largest gold reserves (deposits) after Australia and Russia. GOLD WHERE IT’S FOUND Gold ore (a naturally occurring concentration of a mineral) is found in the Witwatersrand area in Gauteng. This inspired Johannesburg’s nickname “Egoli”, which means “city of gold”. Gold is also mined in the Free State. USES Apart from being made into jewellery, gold is used in tooth fillings and to conduct electricity in space vehicles, cellphones and TVs. DIAMONDS WHERE IT’S FOUND South Africa produces 10% of the world’s diamonds. Mining takes place near Lime Acres, 160km northwest of Kimberley, Northern Cape, and near Alldays in Limpopo. USES This is the hardest natural substance on Earth. Gem diamonds are used in jewellery and industrial diamonds are embedded…

THERE are eight planets in our solar system, but – as far as we know – Earth is the only one with the right conditions for life to exist. That’s because our planet lies within what’s known as the sun’s Goldilocks Zone (or habitable zone) – not too close and not too far from the sun. Our sun is actually a star, and like all stars it releases a massive amount of energy in the form of light and heat. We rely on the sun’s incredible energy to sustain life on Earth. Without it, there’d be no light, no warmth and no life. WHERE DOES THE SUN’S ENERGY COME FROM? The sun is essentially a big ball of hydrogen gas held together by its immense gravity. The pressure and density…

VISOR Gold-foiled visor for sun protection IN-SUIT DRINK BAG (IDB) A tube leads from the plastic water-filled pouch inside the HUT to keep astronauts hydrated. OVER AND OUT Communication system with microphone DISPLAY AND CONTROL MODULE The astronaut can control oxygen, cooling, radio and other systems. Labels are written in reverse so they can read them with a mirror placed on their wrist. GLOVES The gloves have miniature heaters in every finger. SUIT LAYERS The many layers of the EMU suit THE LOWER TORSO ASSEMBLY The pants, boots and lower half of the waist closure. A waist bearing helps the astronaut move and turn and a metal seal closure connects the lower torso to the hard upper torso. THE EMU SPACESUIT THE Extravehicular Mobility Unit (EMU) has been used since…

COMPOST is decomposed organic material. When you add it to the soil in your garden it acts as a fertiliser by helping to replace the nutrients the plants have absorbed. Compost also adds texture to the soil, helping it to absorb and retain moisture from the air – which saves water. And making compost is a good way to recycle and reduce how much rubbish you throw away. Here’s how to make your own with the help of an adult. STEP 1 DRILL HOLES Ask an adult to drill holes in the bottom (for drainage) and lid (for air circulation) of the container. Then put the container in the shallow container. TIGHT LID Make sure the container has a tight-fitting lid to keep the soil moist and keep bugs out.…

ANYONE who’s experienced load-shedding in South Africa will agree on how handy a torch can be. The torch or flashlight was invented by Englishman David Misell in 1899. He put three batteries (which had just been invented in 1896) in a tube attached to an electric bulb, and a contact switch turned it on and off. It used to be called a flashlight (though now we generally call it a torch and Americans still call it a flashlight) because it could not give light for long, just a few flashes at a time then the battery would burn out. But batteries became more reliable and the torch was widely used from the 1920s. Today they range from huge ones to tiny ones on a keychain and even underwater torches. So…