Encyclopedia for Children

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CONTENT EARTH AND SKY

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STARS – SOLAR SYSTEM – THE EARTH – VOLCANOS – LAND AND SEA – CLOUDS – CLIMATIC ZONES – ENVIRONMENTAL PROTECTION

FASCINATING NATURE

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THE STORY OF LIFE – ONCE UPON A TIME... – GREEN ZONE – LOVELY FLOWERS – INVERTEBRATES – FISH – AMPHIBIANS AND REPTILES – BIRDS – MAMMALS – PRIMATES – MAN

TS OUR WORLD

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PREHISTORIC WORLD – PAST CIVILIZATIONS – BARBARIANS AND KNIGHTS – EXPLORERS – NEW WORLDS – SPIRITUAL PATHS – INVENTIONS – PRESENT TIME – THE MAGIC OF BOOKS – MUSIC – BEHIND THE SCENES – CLOSE-UP – DANCING WORLD – SPORTS

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EARTH AND SKY

THE EARTH Earth looks like a beautiful blue ball from space. In fact, it is a slightly flattened at the poles. Clouds are continuously swirling above the surface, covering the darker patches of land. Let’s take a look at our planet, which has been studied for thousands of years, but is still full of mysteries!

In the North and South Pole regions, there is at least one day in a year when the sun doesn’t rise and another day when the sun doesn’t set. This is the home of month-long polar days and polar nights.

ocean fault lines mark the borders of tectonic plates

How does it move?

The Earth rotates around its imaginary axis. One rotation takes a little less than 24 hours – 1 Earth day. The Earth’s axis is tilted in a 23°27´ angle towards the orbital plate. That’s why days and nights are not the same lengths.

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Summer in the North

Winter in the North Sun

Winter in the South

Summer in the South

Our planet travels around the Sun in an elliptical orbit. It takes an Earth year (almost 366 days) to orbit the Sun. Since the Earth’s axis is tilted, the radiation from the Sun reaches the planet’s surface at an angle. This causes the change in the seasons. However, at the Equator, the temperature is continuously high because there, the rays of sunlight arrive at right angles with the sun directly overhead.

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Pulled in

The Earth is kept in its orbit by the Sun’s gravitational pull. But the Sun’s gravitational force also attracts the water or other objects on our planet’s surface.

Tides are caused by the gravitational pull of the Sun and the Moon.

The tide is the lowest (ebb) when the Sun and the Moon are at right angles. This is called ‘neap tide’.

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The tide is highest when the Sun and the Moon are in the same plane (New Moon and Full Moon).

Interior Structure

The Earth’s interior is divided into three zones: the thin outer crust, the mantle below that and the core. The crust and the upper, more rigid part of the mantle together are called the lithosphere (rock shell). Below that, the mantle is malleable. Even deeper, regardless of the extreme heat, the mantle is kept solid by the extreme pressure. The core is also divided in two: the inner core is solid, while the outer core is molten iron and nickel.

the 2,900 km thick mantle is mainly partially molten, hot rock

When two plates collide, the folding creates mountains. the thin (5-65 km) rigid crust

the hot, 2,200 km thick outer core is liquid metal

the rigid, hot (6,300 ˚C) inner iron core (1,200 km thick)

Basic Plate Tectonics

The Earth’s crust is not in one piece but made up of ‘plates’, which are floating on the molten mantle (the asthenosphere). The plates move 1-2 cm per year, getting closer to or further from each other.

In both cases, molten rock (called magma) gets to the surface along the fault lines. Each new layer of lava that sets on the surface makes the plate thicker. Volcanic activity used to be more intense on the young Earth. divergent plates

When two plates converge, one slides under the other.

continental plate

The boundaries of tectonic plates The plates carrying land are called continental plates; the plates carrying oceans are called oceanic plates.

The hot rock under the surface is continuously moving, carrying the plates on its ‘back’.

Moving continents

The tectonic plates and the continents they’re carrying are moving away from each other.

But they used to be parts of a huge supercontinent, which you can easily reconstruct; just imagine putting the current continents together like a puzzle.

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oceanic plate

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FASCINATING NATURE – PLANTS

GREEN ZONE

Plants are living organisms that construct their own organic body from the inorganic materials found in their environment. They use the carbon dioxide in the air, the water from the soil and solar energy for the process. Unlike animals, plants are fixed to one place during their entire life.

Plants are the key to life on Earth. We could not exist without them. Luckily, plants propagate easily and are capable of continuous regeneration. They provide oxygen and nutrients by recycling minerals. We also use them to build houses, make our clothes, tools and machines. Plants also turn nature and our own environment into a beautiful space.

Trees host several hundred species of insects and mites providing sufficient food for bird and other creatures, enabling the forest to maintain a rich ecosystem.

Berries

Today, it is nearly impossible to find patches where nature is still in its original state. Our hunting and gathering ancestors lived in harmony with nature and ate a lot of berries.

The edible ones were chosen to be ‘cultured’. These are still grown for their high vitamin content.

Warning! Some wild berries are poisonous!

Wood is a valuable raw material because of its mechanical characteristics: tensile and compressive strength, high flexibility, light weight, workability, insulating and ventilating features. Today, in the ‘plastic-age’, wood is still impossible to replace in many cases.

In public places, parks and gardens we can encounter trees from all over the world.

Arboretums and botanic gardens play an important role in maintaining diversity.

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Humus – Fallen leaves, decaying branches and logs provide sufficient material for humus formation, with the valuable soil becoming thicker and thicker.

The major organs of a plant are root, stem, leaf and flower. The roots stabilise the plant and absorb nutrients. The stem holds the leaves and flowers, defines the shape of the plant and distributes the nutrients.

The leaf converts solar energy, carbon dioxide and nutrients into organic materials by photosynthesis.

Flowers are the reproductive organs of plants.

Trees

Trees are the tallest plants on the planet. Some 10% of all land surface is covered by forests and woods, which generate a huge amount of biomass (living matter) every year by recycling their leaves and fruit. When their life process is disturbed (deforestation), the balance of atmospheric gases is upset, which has far-reaching consequences.

The growing part of the trunk is called the cambium agering

the outer layers of the bark are older; the inner layers are younger

Where cold and warm seasons alternate, growth speeds up in spring and early summer.

Thickening tree trunks form light-coloured rings. Later, a darker layer appears. These two kinds of rings mark a year of thickening. New parts grow inside the trunk, while the old parts are outside.

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The bark is the tree’s ‘shield’, protecting it from cold, heat, dehydration and pathogens. Its colour and pattern are characteristic of the species.

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Pine needles remain green all year round, that’s why pine trees are called evergreens.

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FASCINATING NATURE - MAN

HUMAN BODY

Man is the most advanced life form on Earth. Unlike other living things, man is distinguished by using language. Its superiority is marked most prominently by the size of the skull. This bony structure protects the brain, the control centre of all bodily systems. Let’s look at the more important systems.

Cells, tissues, organs

Internal structure of bones Bones serve as the frame of the body, so they have to be extremely strong. All bones are wrapped in a greyish membrane called periosteum. Underneath, lies the hard cortex or compact bone (tissue of microscopic bone cells) with blood vessels and nerve tracks running lengthways. Inside that, the spongy bone can be found, which contains the bone marrow.

skull

The body is made of billions of cells, which have different specialised functions. Cells of similar functions form tissues, which are the building blocks of organs. Organs also work in groups as organ systems, which are controlled by the brain.

knuckles mandible

neck muscle

radius and ulna

trapezius elbow-joint

Skin

humerus

spinal column

The body is protected by multi-layered skin. In the layer beneath the outer epidermis, new skin cells are generated to replace the dead ones.

shoulder-blade chest with the ribs pelvic bone (hips)

epidermis thigh-bone dermis

hair follicle

knee-cap

gluteus and crural muscles

splinter-bone shin-bone

The musculoskeletal system

Muscles and bones create the largest organ system of the human body.

Body movements are the result of the harmonised operation of the skeleton, the muscles, the brain and the nervous system. Muscles only work effectively if there is sufficient amount of protein. During movement, muscles burn nutrient molecules and energy is released. Muscles are connected to the bones by tendons. When contracted, tendons change the position bones.

anklebones sartorius muscle

Joints

Usually, the locations of muscles’ origin and insertion, the points where the muscles are anchored, are the joints.

Joints allow movements of the skeleton.

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toe knuckles

Bone types

There are four major bone types: • long bones: shin, thigh, arms and fingers • short bones: wrist (carpal bones), ankle (tarsal bones) • irregular bones: facial bones, back • flat bones: ribs, skull, shoulder blade

• Skeletal muscle is also called striated muscle. The name refers to its structure: it consists of a series of complex musclefibre bands. Small muscles have only a few fibre bands, large muscles may have several hundred.

• Our smooth muscles are responsible for the involuntary movement of our internal organs (stomach, bowels).

• The third type is called heart (cardiac) muscle. Heart muscles are controlled by the nervous system but also affected by hormones. These muscles involuntarily contract 150 times per minute. This is caused by a group of special muscles in the right atrium. They generate the rhythm (as a pacemaker would).

There are over 600 muscles all over the human body, everywhere from head to toe. Most of them are skeletal muscles, moving different parts of the skeleton.

Nervous system

Its components are the brain, spinal cord and nerves. The most advanced is the brain, the organ responsible for thoughts, learning, memories and feelings. Different senses and actions are controlled by different parts of the brain. The spinal cord is the reflex centre, a band of nerve fibres inside the spinal column. Nerves originate both from the brain and the spinal cord and carry the information in the form of electrical signals. Many activities are automatically carried out by the body – breathing, walking, digestion, etc.

The ‘orders’ are carried at an astonishing speed: 300 km/h.

Another control system of the body is the endocrine system, which affects the operation of the organs by chemical molecules called hormones. Hormones are produced in glands positioned in various parts of the body.

The contraction and relaxation of muscles and muscle groups enable our movements.

For example, to bend your arm, your biceps (two-headed muscle) needs to contract. And the spinal cord informs the brain about that.

intercostal muscle upper arm muscles abdominal muscle

finger muscles

Digestion

Achilles tendon

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gullet

liver

stomach

small intestine large intestine rectum

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calf muscle

Digestion begins in the mouth, where, after the teeth have ground it, food is broken down by saliva.

The tongue takes the bite of food covered in saliva to the gorge. Then food is swallowed and gets to the throat. When swallowing, the throat flap blocks the windpipe, so that the food wouldn’t go down the wrong way. Inside the throat, the muscles contract and relax as a reflex, pushing the food down to the stomach.

The stomach produces digestive enzymes to break down the food. It also releases hydrochloric acid which destroys bacteria. Carbohydrates get into the intestines much quicker than foods containing fat.

Food is further broken down in the small intestine.

Nutrients are absorbed through the intestine walls into the bloodstream and carried everywhere in the body.

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OUR WORLD - THE MIDDLE AGES

BARBARIANS AND KNIGHTS Thinking about the Middle Ages, lords and ladies feasting in grand halls of castles, serfs working the land and armoured knights come to mind.

This era brought big changes in Europe. In the territory of the West Roman Empire, German kingdoms were founded. Trade declined, people lived off the land. Feudal lords held all power and created the feudal system.

Antiquity’s knowledge disappeared, which is why the early Middle Ages are called ‘dark ages’. The golden era of the Middle Ages arrived in the 13th century, but soon the Renaissance replaced this period in Europe.

Country life

The medieval village was owned by the feudal lord. The land was divided in long patches, and the serfs (peasants) worked them. Most of the crop they could keep. They worked hard to be able to pay their taxes to the Church and the feudal lord in crops or by working.

Peasant women worked around the house, helped on the land work, spun yarn and weaved. From time to time, serfs rose against their feudal lords. But these uprisings were almost always suppressed.

Castle – Feudal lords lived in castles near the villages. These fortresses gave protection to the villagers in times of war.

City life

As trade picked up, tradesmen became more and more rich and influential. Cities with huge markets served as trading hubs. Craftsmen lived in cities too. They founded guilds safeguarding their own interests.

Many cities were surrounded by stone walls.

These cities could become independent from the feudal lord, and establish a sovereign authority.

Feudalism

Kings granted pieces of land to their vassals and noblemen, who in turn were obliged to provide military support. These noblemen also granted smaller pieces of land to nobles and knights of lower ranks. The vassal served the lord, and they were brothers in arms.

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TIMELINE

Crusades

800 Charles the Great, king of the Franks, builds an empire including the whole of Western Europe 1000 Saint Stephen establishes the Hungarian Kingdom 1000–1299 The peak of the Middle Ages 1300–1500 Late Middle Ages 1320 Renaissance begins in Italy around 1348 Plague epidemic in Europe 1458–90 King Mathias rules Hungary 1492 The discovery of America

In 1071, Seljuk Turks defeated the Byzantine army, occupied Jerusalem and persecuted the Christians.

Christian Europe was outraged, and they organised crusades to reoccupy the Holy Land (Palestine).

To protect pilgrims, religious, military orders were founded: the Johannites or Hospitallers, the Templars, German orders, etc. Starting from 1096, there were at least four crusades. None of them were successful, but introduced Eastern culture to Europe.

The Black Death Medieval cities were overcrowded. No sewage or waste disposal system existed.

Subsequent plague epidemics struck Europe from 1348.

The deadly disease killed 20-30% of the population.

Knights

Feudal lords wore armour in battle. They were called Knights. A knight dressed in full body armour could only be recognised from this coat of arms. Knights’ lives involved frequent wars, battles, hunts, tournaments and feasts.

The Children’s Crusade took place in 1212.

During the long journey to Jerusalem, thousands of Christian children died of hunger; others were sold as slaves.

The booths of merchants and showmen were on the city square. The scaffold was also placed here, where felons were put in the stocks or were executed.

The jewels of medieval cities were the cathedrals.

These were built first in Romanesque, later in Gothic style, representing God’s power. Monks and nuns belonging to different orders (for example Benedictine, Cistercian, Franciscan and Dominican) lived in monasteries.

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Cathedrals and monasteries

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OUR WORLD

THE BEAT OF MUSIC Music is part of our everyday life; an art form expressing our feelings and temperament. Singing was a social activity in early civilisations; working men used the rhythm of songs to harmonise their movements, religious rituals were accompanied by dancing and singing, music served as a form of encouragement before hunting and battles. In medieval times, grand musical events, spectacular ballets and operas were available for those who could afford the tickets.

Such shows were performed by professional musicians, singers and dancers.

Types of musical instruments with examples

woodwinds (horn, flute, trumpet, saxophone, trombone)

string-keyboard instruments (piano, organ, harpsichord)

string (harp, guitar, violin, cello)

percussion (drum, gong, cymbal, triangle, bell, rattle, xylophone)

Singing voice and instruments

Our voice is a gift from nature. We are born with it, and we use it naturally. The singing voice is the most expressive instrument of all. The vibrations emitted by the sound source cause the air to move, creating sound waves.

Different parts of a musical piece are sung by many singers at the same time without accompanying instruments.

This is called vocal music. But musical sounds can be made not only by our vocal cords but also by instruments.

Many thousands of years ago, mankind discovered the musical properties of objects by blowing air inside a hollow bone, shell or straw.

Modern instruments are more complex.

New musical genres appeared in the 20th century, such as jazz, blues, country, rock, pop, soul, rap, and counting. New sound technology, performance and storage options are provided by electronics, synthesisers and computer technology.

Béla Bartók (1881-1945), collector of folk music

Besides composing stage works (Bluebeard’s Castle, The Wooden Prince, The Miraculous Mandarin), orchestral and choral works (Cantata Profana, piano concertos, Divertimento...), he travelled with his phonograph and recorded folk music in Slovakian, Transylvanian, Romanian and Algerian villages. Zoltán Kodály drew his attention to the importance of collecting unrecorded folk music. If not for Bartók’s efforts, this cultural heritage would have been lost. Folk music also helped him find his own style of music.

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Recording

In modern studios, songs can be recorded in sections again and again, so that the best quality recordings can be edited into a song. Singers can record their work as separate parts, and the studio can edit them together or add background music if needed.

We hear our own voice differently than everybody else because the sound gets to the inner ear via our own skull bones. But to the audience, our voice is transmitted through the air, so it sounds different.

Black music

Scat is a musical genre of black singers. It is very emotional and expressive but uses syllables without meaning. According to legend, the great jazz trumpeter, Louis Armstrong invented it, when he accidentally dropped the sheet of paper with the lyrics on it.

Classical or pop?

Many don’t like classical music; they consider it to be too difficult.

Musicians, directors and agencies work hard to win over a wider audience for this valuable genre. Theatres often stage classical operas, using spectacular sets and costumes, printing colourful programme leaflets to promote classical genres. Hit plays are often broadcast live on TV; huge concerts of great sound quality are always successful; summer concert series are organised outdoors; classical masterpieces of eternal value are sold on cassettes, CDs and DVDs.

Electronic music

Record-holders

The world-famous British prog-rock band Queen had concerts on all five continents and had the largest audience ever. The band was given awards several times, even after the death of their lead vocalist, Freddie Mercury (died in 1991).

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In the 1960s, synthesisers appeared, which - unlike traditional (acoustic) instruments - can produce electronic music.

In theory, these can create any sound and can emulate any instrument. The musician synthesises, compiles the sounds from different elements. The keyboard version is the most popular.