Ou. Solar System !

A solar system is simply a sun and all the bodies around it that it controls by gravity. Out solar system is made up of all the planets, moons, asteroids, and comets that our sun controls by gravity. Out earth is simply one of the planets.

The planets vary greatly in size and distance from the sun. Mercury is the smallest planet and the nearest to the sun. It goes around the sun in only 88 days. Venus is about 68 million miles from the sun, and goes around it 225 days. The earth is 93 million miles from the sun. Mars is about 142 million miles from the sun and goes around it in 687 days.

Jupiter, which is about 483 million miles away from the sun, takes 12 years to make one trip around it. Saturn, 886 million miles form the sun, takes 29 1/2 years to make one orbit. Neptune takes 165 years. so you see, while these planets are part of out solar system, each one is quite different and exist under very different conditions.

What is Virus ?

Virus are very small particles which may cause disease in man, animals, and plants. The words "particles" seems a stranger way to describe them, so let's see why it used.

Virus are so small, they will pass through the finest filters. They cannot be grown in sugar solutions, but will grow and multiply in the presence of living tissue. They are parasites and depend completely upon their host. Viruses are too small to be seen by ordinary microscopes - they have to be photographed through electron microscope.

Viruses cause many diseases with which we are familiar. In attacking organs of the body, each group of viruses causes a different group of diseases. Some of the diseases caused by virus that attack the skin are chicken pox, smallpox, measles, German measles and fever blisters.

Other viruses cause diseases of nerve tissue, such as rabies, brain fever and infantile paralysis. A third group of viruses cause diseases in the internal organs. Yellow fever, influenza, the common cold and viral liver inflammation are examples of this group.

How Does a Volcano form?

In February, 1943, in the middle of a cornfield in Mexico, people saw a rare and amazing thing taking place. A volcano was being born ! In three months it had formed a cone about 300 metres high. Two towns were destroyed and a wide area damaged by the falling ash and cinders.

What makes a volcano form? The temperature under the earth becomes higher and deeper you go. At a depth of about 20 miles, it is hot enough to melt most rocks.

When rocks melts, it expands and needs more space. In certain areas of the world, mountains are being uplifted. The pressure becomes less under these rising mountains ranges, and a reservoir of melted rock ( called "magma" ) may form under them.

This material rises along cracks formed by the uplift. When the pressure in the reservoir is greater than the roof of rock over it, it bursts fourth as a volcano.

In eruption, hot gaseous liquid, or solid material blown out. The material piles up around the opening, and a cone-shaped mound is formed. The "crater" is depression at the top of the cone where the opening reaches the surface. The cone is he result of a volcano.

The material coming out of a volcano is mainly gaseous, but large quantities of "lave" and solid particles that look like cinders and ash are also thrown out.

Actually, lava is magma that have been thrown up by the volcano. When the magma comes near the surface, the temperature and the pressure drop, and a physical and chemical change takes place that changes the magma to lava.

Carbon.

Carbon is important to all forms of life. It makes up less than 1 percent of all matter, but everything that lives or has lived contains this element. The bodies of all living things are made up of compounds containing carbon, and where it found in any quantity in the earth, life has probably existed.

Plants get carbon from carbon dioxide gas of the air and use it in building up their roots, stems, and leaves. Animals get it for food from plants. At the same time, carbon dioxide is being returned to the air by animals when they breathe, and by plants when they decay.

Of all the forms of carbon, the best-known, and perhaps the most valuable to man, is coal. Coal is about four-fifths carbon, the rest being hydrogen and other elements. The attraction between carbon and oxygen is almost like that between a magnet and iron.

This is one of the reasons why coal is so valuable. When coal is put into fire, its element, particularly its carbon, burn or combine with the oxygen in the air. This burning produces heat energy, which used by man in many ways.

Carbon atoms can attach themselves to each other and to the atoms of other elements. They combine in many different ways to from many carbon compounds. One of the simplest one is carbon dioxide, which given off into the atmosphere when carbon burns in oxygen. Carbon monoxide, a poisonous gas, forms when carbon burns where there is not enough oxygen.

Noise.

Sound is the result of vibrations. Vibration is simply moving back and fourth of some object. When the vibration is very regular, when the sounding body sends out waves at absolutely regular intervals, the result is a musical sound. If the vibration is not regular, the effect on your ears is not all pleasing. The resulting sound is "noise".

The three differences between one sound and another are loudness, pitch, and tonal quality. Loudness of a sound depends partly on the distance from the object to the ear and partly on the amplitude of vibration of the sound-making object. Amplitude means the distance the vibrating body moves in its to-and-fro motion. The greater the movement is, the louder the sound will be.

The highness or lowness of a sound is called its "pitch". Pitch depends on the speed of vibration or the sounding object. The greater the number of vibrations that reach the ear every second, the higher will be the pitch.