Wednesday, May 30, 2012

What is Radar and how does it Work?

The word ‘radar’ is an acronym for radio detection and ranging. It is, in fact, an electronic device by which one can detect and measure and invisible flying object’s distance and speed. It can work efficiently under all weather conditions such as fog, mist, smoke, snowfall, storm, cyclone, rains, etc. it is due to these reasons that radar is used in the traffic control room of airports for the guidance of airplanes. It also helps to guide ships.

Working Radar

            The radar works on the principle of echo, much like sonar. The sound waves reflected by some obstacle produce an echo. Similarly, radio waves, which are electromagnetic in nature, also get reflected when they encounter some obstacle in their path. Scientist’s discovered this property of radio waves in 1930. Using this property, in 1395, five radar centers were established in America. Major developments in the field of radar took place during the Second World War. They were of great help in detecting enemy bombers. Since then, many kinds of radars have been developed for peaceful uses also. Now, there are radars installed even in fighter aircraft. Radars help in controlling and guiding the path of unmanned spacecrafts they are also used in giving information related to weather.

            Have you ever wondered how it works? Radars make use of radio waves. These waves re similar to those used in radio broadcasting. However, the radio waves used in radar have higher frequencies. These waves are called microwaves. The speed of these waves is equal to that of light, i.e., 3x108 meters 186,000 miles per second. Each radar centre has a transmitter, which sends out radio waves with the help of an antenna towards an object. It also has a receiver, which receives the radio waves reflected by the object. The receiver has a screen that shows the object’s position in the sky.

            The time taken by the radio waves in sending from the transmitter to the object and returning to the receiver is recorded by radar. By multiplying this tie with the velocity of light, we get twice the distance between the radar and the object. This is how the distance of an object is found with the help of radar. The radar has automatic instruments that perform all these calculations. Initially, radars were very big in size, but today they can fit in our palms.

How did the English Language Originate?

English has now become a global language in the world. It is difficult to get along in life without this language. In many parts it is used as an inherited native language, a second language and a practical language for administrative, professional and educational purposes. Many of the modern ideas of science and technology are communicated only through English. Hench, English is the most important language of the world. Do you now how this language originated?

            Modern English is only about 500 years old. Some five thousand years ago, language of the European family was spoken in European courtiers. They were also spoken by the people of southern Russia and by the wandering tribes between the Rhine River and the Aral Sea. However, the people who spoke this ancient language had dispersed and their language got broken up into several different dialects.

            One of these dialects, known as primitive Germanic or Teutonic, began to split up into their dialects about the beginning of the Christian era. It split up into two basic dialects- East Germanic and West Germanic. The West Germanic dialect again split up into two dialects- High German originated the modern language. And, the Low German gave birth to Dutch and English. English, however, was derived form Low German after many changes and modifications over the years.

            What first developed from Low German, which led to the creation of modern English, was a dialect called old English or Anglo Saxon. It was introduced into Britain about the year 449. It continued up to the year 1150. From 1150 to 1500 AD some changes found their way into it ad it came to be called Middle English. But it is only from the year 1500 onwards the modern English came into regular use.

Tuesday, May 29, 2012

How does a Zip Fastener Work?

            Zip fastener is a fastening device in which two rows of teeth and sockets are brought together in such a way that they interlock. Whitcomb Judson invented the first zip in 1893.

The Zip Fastener an improved method of fastening garments

            Metal zips have lines of tiny teeth, while plastic zips contain small loops on each side.

            Do you know how a zip fastener works?

            When you pull the side of the zip fastener up, it pushes the teeth or loop together. Beneath each tooth in a metal zip fastener is a small space. The slide is narrow at the bottom so that it forces the teeth together as the zip is pulled up. The teeth on one side fit between the teeth on the other side. As they come together, each tooth slips into the socket under the tooth above and the zip stays closed. As the slide moves down, a divider at the top of the slide pulls the teeth apart.

            The top pieces and a bottom piece at the ends of the fastener stop the slide from coming off, though some zips are made to separate completely by pulling one line of teeth out of the bottom piece. Plastic zips have two spiral coils instead of lines of teeth but the principle on which they work is the same.

Where was the Potter’s Wheel Invented?

            The potter’s wheel has always fascinated people. Many children have not seen a potter working. Do you know how these wheels were invented and where? In the beginning, the pots were shaped by hand out of wet clay. Turning the raw lumps of earth o a wheel was developed later.

Potter’s Wheel

            The potter’s wheel was invented in Sumeria, Babylon and also elsewhere in the near east around 3000 B.C. clay pots and already been made for over 5000 years, but they were crude and broke easily.

            Making pottery items on a potter’s wheel is a craft that requires a lot of skill. The potter needs skill not only in spinning the wheel and shaping the pot with his hands, but also in firing the pot in a kiln to harden it. Potters also learned how to glaze coat pots with various substances to make the pots stronger and more decorative and beautiful.

            The invention of the potter’s wheel led to one of the first industries in the world pottery. In earlier days, a skilful potter could make enough pots to exchange them for food and other goods, or sell them for money. Nowadays, potters make pots form clay to sell them in exchange for money. Pots now come in various shapes and sizes and patterns. Some examples of pottery have bee recovered form the ruined cities of Pompeii and Herculaneum that were buried under volcanic ash when the volcano Vesuvius (near Naples, Italy) erupted in 73 AD. Examples of amphorae big pottery jars containing remnants of what was once wine, have been salvaged form ancient sunken ships discovered at the bottom of the Aegean Sea. Pottery shards and even some intact examples of pottery have been found at almost all archaeological sites the world over. This proves that knowledge of pottery extended too much of the ancient world.

How did the Circus Begin?

            Everyone enjoys going to the circus. The amazing tricks take your breath away and the clowns have your sides splitting with laughter. But have you ever wondered how the circus first began? The Romans were the first to use the word circus in the 1st century B.C. the large open area was called ‘The Circus Maximus’. The main attraction in such a circus was a chariot race. The drivers wore helmets and were wrapped in lengths of bright colored flowing clothes. The grounds were so large that they could accommodate around 1, 50,000 people. In those days, Rome had various kinds of entertainments. Jugglers, acrobats, ropewalkers and animal trainers also entertained people in many ways. Eventually all those feats became part of what we call a circus.

Circus

            However, in modern times, the popularity of circuses have dwindled, and animal rights activists have hastened their decline by arranging to have the animals confiscated ad sent to zoos, where they would enjoy better health, food and environment.

            After the fall of the Roman Empire, circuses went into oblivion for many centuries. The first modern circus came into existence in England I 1768, when Philip Ashley turned into a trick rider, and he traced the first ring. The diameter of the ring was 13 meters. The name circus was first used in 782 when charies Hughes set up the royal circus. Many showmen found a new outlet in the circus, as did the ropedancers, acrobats, jugglers and others. In the first half lf the 19th century, many circuses also started in the United States.

            Circus was once popular means of entertainment. Both young and the old loved it equally. In a modern circus, we see many amazing feat like ropewalking, wire cycling, fire eating, weightlifting, flying on trapeze and innumerable animal and bird games. Jugglers, acrobats and clowns join in to add to the entertainment. The circus is a dying industry today, as people seek newer forms of entertainment.

            Did you know that the world’s largest permanent circus is circus Las Vegas, Nevada, USA? This circus was opened on October 18, 1968. It covers an area of 11,984 sq. meters. The largest traveling circus was the gold unit of Ringling Bros. and Barnum & Bailey circus. It was used for a show at Sapporo, Japan on July 1, 1988. The largest circus crowd comprised 52,385 people who attended the performance of the greatest show on earth in New Orleans, bros. and Barnum & Bailey circus, an American circus, was formed when two of the world’s biggest rival circuses, finally merged. Currently, it is the largest and the most successful of the few remaining American circuses. It can be said to be performing continuously since 1871.

How does an Aerosol Spray Work?

            Aerosols were patented in the United States of America in 1914 and have been increasingly used since the early 1950s. Aerosol cans and bottles are used to spray paints, perfumes, deodorants, furniture polish, oven cleaner, pesticides and many other liquid products. There is hardly any liquid, which does not come in an aerosol container. Do you know how the aerosol works?

The Functioning of Aerosol Spray

            Initially, the can is filled with the liquid to be sprayed and the propellant. On pushing the press button, the product is force dup the dip tube and comes out as spray from the hole at the top. The top hole is very narrow and causes the liquid to break up into a fine, mist-like spray.

            Inside the can, the propellant is a gas under pressure. The gas is usually a chlorofluorocarbon CFC, which forces the liquid in the tube out of the nozzle at the top. The top of the can contains a valve with a spring that closes the valve when the top is released by means of the press button.

            However, chlorofluorocarbons are very damaging to the atmospheric ozone layer. This has forced scientists to look for alternatives.

            As an aerosol contains a gas under pressure, it is dangerous to puncture or heat the can. If heated, there are possibilities that the can may explode.

How was the Rocket Developed?

            Today, the word rocket as found broad uses in almost all aspects of development. Missiles used in wars are a form of rockets. The space satellites used to collect information about planets and their satellites are launched into orbit by rockets. We hear of fireworks called rockets. Whatever be the context in which the word rocket is used, one thing is certain- all rockets function on the same principle. A rocket works on the principle of Newton’s third law of motion. According to this law, to every action there is an equal and opposite reaction.

Rocket

            The gases produced by the burning of fuels inside the rocket chamber come out of a nozzle and produce a great force. As a result of this reaction, the rocket gets the necessary push to move forward. Do you know how the rocket was developed?

            The story of the development of the rocket starts with china. Rocket development took a very long period of time. No single person can be credited with its invention. In the year 1232, the Chinese and arrows of flying fire in the wars against the Mongols. These arrows were also a kind of rocket. By 1275 rockets were being used in India, England, Arabian countries, Germany and France and few other countries. During the early 1800s, Colonel William Congreve of the British army developed rockets, which were used in every war thereafter. In 1926, Robert h. Goddard America developed liquid propelled rockets. Goddard today is known as the father of the modern rocketry.

            High speed rockets were especially developed for space explorations. The space age began on October 4, 1957 when Russia launched its first satellite sputnik I. today, we have solid and liquid propelled rockets, nuclear and electric rockets. Nowadays, multistage rockets are used for launching the space shuttle or putting satellites into either earth orbit or on exploratory voyages to other planets.

The Submarine Invented

How was the submarine invented?

            The submarine has been one of the most important inventions man has ever seen. A submarine is a vessel that can travel on the surface of the water as well as underwater. It is shaped like a cigar, and can be lightly closed from all sides. There are different types of submarines, which can travel underwater at different depths. They are usually powered by diesel electric engines, but some are nuclear powered also.

A Submarine

            Man has always wondered about the secrets hidden in the bottom of the sea. He has long made efforts to reach the bottom of the seas in search of diamonds and pearls. In order to succeed in his attempts, he tried to invent some device that could travel under water. French author jules erne wrote a novel called 20,000 leagues under the sea more than 150 years ago, in which he described what was obviously a nuclear submarine- even though nuclear technology and submarines themselves had not been invented then. Could this be a case of ESP?

            Nevertheless, Cornelius van Drebbele of Holland devised the first submarine – a boat capable of traveling under water- in 1620. This submarine was made of wood and was wrapped in leather. It could submerge only to a depth of 3 to 4 meters in seawater. After that, many efforts were made to develop other types of submarines up to the end of the 18th century. By 1727, fourteen different types of submarines had been made in England alone.

            In 1880, a submarine propelled by a steam engine was developed. Later on, submarines powered by gasoline and electricity also come into operation. Submarines were successfully used in the First World War (1941-1918). During the Second World War (1939-1945), submarines powered by diesel were also used in sea warfare. Now nuclear powered submarines have bee developed. The first nuclear submarine was launched in 1954 by USA. It was named nautilus after the submarine of the same name in Jules Verne’s fictional work, 20,000 leagues under the sea.

            Submarines are sued for various purposes. They are very useful in oceanography. Missiles and torpedoes are launched from them to destroy enemy ships.

            Some nuclear submarines are even capable of launching cruise missiles and ICBMs even when they are submerged at great depths. Modern submarines are equipped to track and destroy enemy submarines. Every submarine has emergency equipment that helps its crew to escape to safety in case of danger, such as serious damage suffered by the vessel. Submarines are now a vital part of every country’s defense system. However, only a few advanced countries know how to make them.

Telephone Invented by Alexander Graham Bell

How was the telephone invented?

            The telephone was become an indispensable part of our life. Can you imagine your life without the telephone? The telephone is used every where, in business, offices, homes and factories.
Alexander Graham Bell

            The world telephone has been deriving fro the Greek words tele meaning far and phone meaning sound. Thus, the word telephone means a device that carries sound to distant places. The story of the invention of the telephone is very interesting. Let us go back to June 2, 1875, when Alexander graham bell was working along with his assistant Thomas Watson on some problem related to telegraphy. Bell was on the telegraphic receiver in one room, whereas his assistant was in another room. Watson created some vibrations on an iron strip. When bell rushed to the other room, he found the iron strip vibration between the poles of a magnet was producing electric current in the connecting wire. It was this historic observation that led to the birth of telephone. Graham bell first demonstrated the telephonic conversation on March 10, 1876.

            Do you know how the telephone works? The telephone consists of two main parts the mouthpiece and the earpiece. The mouthpiece of the telephone works as a transmitter whereas the earpiece works as a receiver. Both are enclosed in one cage and are connected by a line wire. When we speak into the mouthpiece, a diaphragm attached to it starts vibrating. In accordance with produced. The telephone line wire to the receiver of another telephone carries their current. This varying current produces vibrations in the diaphragm attached tot eh receiver, which is then converted into replicas of the original sound waves. As a result the person at the other end is able to receive the voice of the speaker. The same process is repeated between our receiver and the mouthpiece of the telephone t the other end. In this way, two people can talk with each other on the telephone.

            Today, each country has a vast network of telephone lines and telecommunication satellites. You can now talk to a person on the other side of the globe because of this invention by Alexander Graham Bell.

Instituted the Nobel Prize

Who instituted the Nobel Prize?

            Nobel Prize is considered to be the most prestigious award in the world. It is awarded each ear to people who make outstanding contributions in the fields of science, literature or in promoting world peace.
Alfred Bernhard Nobel

            Do you know how and by whom the Nobel Prize was started? It was started by a Swedish chemist, Alfred Bernhard Nobel who in his will, directed that the income from his $9-million estate should be used to fund five annual prizes. Alfred Nobel was born in Stockholm on October 21, 1833. he invented dynamite, an explosive that is widely used for breaking rocks, oil exploration and warfare. He earned a vast fortune from his invention. Apart form bringing him wealth, this invention also bought him will deserved fame. When he died on 10th December 1896, he left behind a sum of 90, 00,000 dollars- a considerable sum in those days.

            The Nobel Prize is the most coveted and respected prize in the world. This prize is given to people who make the most outstanding discoveries or inventions in five fields, namely, physics, chemistry, literature, physiology or medicine and peace. The prizes were first presented in 1901. Later, a sixth award for economic was added and first awarded in 1969 as the Nobel memorial prize.

            Every Nobel laureate gets a gold medal, a certificate and a large sum of money. One prize is awarded in each field, every year. If there are more than one recipients of the prize in one field, the prize money is shared equally amongst all the winners.

            The first Nobel prize was given to Wilhelm K. Roentgen on 10th December 1901 for his outstanding research on x-rays. The prize money was 40,000 dollars. The winners of this prize are treated with the greatest respect and admiration all over the world.

            A council called Nobel foundation of Sweden awards the Nobel prizes. The royal academy of sciences, Stockholm, selects the best scientist of the year in the fields of physics and chemistry. The Caroline institute of Stockholm selects the best man in the field of medical science, while the Swedish academy of literature does it for literature. Similarly a committee of five persons appointed by the parliament of Norway selects the best people who deserve the peace prize.

            Some of the may many outstanding people of the world who have received the Nobel prize are- Albert Einstein, George Bernard Shaw, Rabindranth Tagore, Sir C.V. Raman, Hargobind Khorana, and Mother Teresa.

            The youngest man to receive a Nobel prize was sir William Lawrence Bragg of England, who received the Nobel prize for physics when he was only 25 years of age.

            Nobel became so well-known that the 102nd element to be discovered was named nobelium in his honor. The Nobel institute of Sweden is also named after him.

Saturday, May 26, 2012

Adopted Names of Weekdays

How were the weekdays named?

            Ancient man had divided the days of a year into months only. When man began to trade, he felt the need for a break from business, construction and professional activities. He needed time for religious activities, festivals and rest. Different places in the world had their own systems. Some places had a break after five days, some after seven days and others after ten days.

Weekdays are derived from the Anglo-saxon System

            The Babylonians observed a break after every six working days. They adopted the seven day wee, as they regarded the number seven as sacred, and every seventh day was treated as a special day. The Jews, too, had a break after every six days, which they called the Sabbath day. The Egyptians next adopted the seven day cycle followed by the Romans. This seven day cycle was adopted by many nations, though they were known by different names.

            The Egyptians also adopted the seven day system based on the four phases of the moon- new moon, quarter moon, full moon and last-quarter. Each phase takes approximately 7 days each. The Egyptians named the seven days after the sun, the five then known planets, and the moon. The names were Sunday, Monday, Mars days, Mercury day, Jupiter day, Venus day and Saturday (Saturn’s day).

            The present day names of the week are derived from the Anglo-Saxon system. The days have been named after their gods, many of which are old Germanic and Norse gods like Woden and Thor.

            Sunday is named after the sun god, and was called sunnandaeg. The moons day is monandaeg or Monday. The next day named after the planet mars, was called tiwesdaeg or Tuesday. Instead of mercury’s name, that of god Woden was given to Wednesday. Jupiter’s day became the god Thor’s day, thursdaeg or Thursday, the day of Venus was named after the wife of Odin, Frigga as Friggdeg or Friday ad Saturn’s day is saeterndaeg or Saturday.

            A day used to be measured to be the interval of time between the sunrise and the sunset, but the Romans considered one day to be from midnight to the next midnight which is what the world has adopted today.

Seasons Change from Revolution of Earth

How do seasons change?

            We know that the earth revolves around the sun and also rotates at its own axis. Days and nights are caused by the rotation of the earth at its axis. The axis of the earth makes an angle of 23 ½ degrees with the vertical. It is this inclination which causes changes in seasons. Due to its inclined axis, as the earth revolves round the sun, the sun’s rays hit the ground at different angles at the same place on the surface of the earth at different times of the year.

Earth's revolution around the Sun causes seasons

            Due to this variation in angles, the distribution of the solar heat is not the same at the same place through out the year. This uneven distribution of solar heat on the earth makes the summer or winter seasons.

            If we look at the picture, we see that in June, when the northern hemisphere is tilted towards the sun, it is summer in Europe, Asia and northern America northern hemisphere and winter in the southern hemisphere. Six months later, in December, the southern hemisphere is tilted towards the sun, so it is summer in the southern hemisphere but winter in the northern hemisphere.

            On March 21 and September 23 of every year, the sun is exactly over the equator. On these days, the duration of the day and the night is the same 12 hours at every place on the earth. From March 21 to June 21, the sun advances form the equator to the tropic of cancer. This results in hot season in the northern hemisphere, and days become longer and nights shorter. During this period, it is winter in the southern hemisphere.

            From June 21 to December 22, the sun advances towards the tropic of Capricorn. This causes the summer season in the southern hemisphere and winter in the northern hemisphere. In the northern hemisphere, the days are shorter and the nights are longer during this period. After December 22, the sun again starts moving towards the north and reaches the equator again on March 21. During these periods, the days in northern hemisphere start getting longer and the nights shorter.

            In March and September, the sun is overhead at the equator, and the hemispheres experience either autumn or spring. Thus, the revolution of the earth around the sun and its rotation at its own inclined axis changes the seasons as well as the duration of the days and the nights.

Atmosphere

What is the atmosphere?

            Atmosphere is the blanket of air that envelops the earth. It contains many gases and particles of various materials. Among the gases of the atmosphere, nitrogen constitutes 78%, oxygen 21%, carbon dioxide and other gases 1%. The atmosphere also contains minute particles of water vapor, methane, nitrous oxide, carbon monoxide, hydrogen, ozone, helium, neon, and krypton and xenon gases. In addition, sand particles, smoke, salt particles, volcanic ash particles, meteoric dust and pollen are also present in the atmosphere.

Atmosphere

            The atmosphere is dense near the earth’s surface, but becomes rarefied as one goes higher up. It is estimated that the atmosphere extends up to the exosphere, which is more than 500 kilometers above the earth’s surface. It is made up of many layers. The pressure, density and temperature of the atmosphere vary with its height above the earth. At a height of 6 kilometers, the air pressure is reduced to half of what it is at the earth’s surface. Similarly, the temperature falls by 1 degree Fahrenheit for every 91 meters we ascend.

            On the basis of its physical properties, the atmosphere has been divided into the following five layers:-

            1. Troposphere: Troposphere extends from the earth’s surface to a height of about 17 kilometers. It accounts for 75% of the total weight of the atmosphere. It is the most important layer, as almost all the living beings inhabit this part. As one goes higher, the temperature falls. Rain, clouds, storms and snow are formed in this part.

            2. Stratosphere: Stratosphere extends up to a height of about 48 kilometers. Its upper portion contains ozone, which absorbs ultra-violet rays coming from the sun. These rays are very dangerous for living organisms. There are neither strong winds nor varying temperatures in this layer.

            3. Mesosphere: Mesosphere starts after a height of 50 kilometers. Here the temperature is significantly low and it is the minimum at a height of 85 kilometers.

            4. Ionosphere: The atmospheric layer above the mesosphere and up to a height of about 500 kilometers is called ionosphere. It contains only charged particles, which reflect the radio waves towards the earth and make radio communication possible.

            5. Exosphere: It is the outermost layer of the atmosphere. Here the density of the atmosphere is very low. This part contains helium and hydrogen, and hence the temperature is very high in this layer.

            The atmosphere is extremely useful for life on earth. Without it, no living being can survive. It protects us from the dangerous radiations of the sun. Almost all meteors radiations of the sun. Almost all meteors falling towards the earth get destroyed; they burn up due to resistance ad friction offered by the atmosphere.

The Calendar Started

How was the calendar started?

            Since the beginning of civilization, man has been observing the sunrise and sunset, and experiencing the occurrence of the day and night. He also observed the various phases of the moon, from one full moon to the next, and the cyclic change in the seasons. He realized that crops did not grow at all times nor was the temperature uniform throughout the year.

Roman Calendar

            With fast developing science, man understood things more correctly. The time taken by the earth to complete one rotation on its axis came to be called as day and night. The time taken by the moon to complete one revolution around the earth was called a month, and the time taken by the earth to complete one revolution around the sun as one year, which comprised 365 days.

            The Egyptians were the first to have a calendar of one year comprising 12 months, each of 30 days. Five extra days were added at the end of the year, thus making a total of 365 days. The people of Greece used the lunar calendar.

            The roman ruler Julius Caesar took a major step in 46 B.C. he sought the help of the Greek astronomer Sosigenes, to adopt uniform calendar. He finally accepted the calendar based on the time take b the earth to complete one revolution around the sun, which is 365 ¼ days; this is known s the solar calendar. The extra quarter of day caused confusion, so Caesar ordered that the ear 46 B.C. should have 445 days so as to catch up.

            The astronomers of Caesar finally adopted a year consisting of 365 days, and every fourth year had 366days, so that one-fourth of a day left out every year was compensated in the fourth year. This fourth year was called the leap year. Any year divisible by the number 4 was taken to be a leap year.

            365 days of a year were divided into twelve months. The months January, March, May, July, august, October, and December consisted of 31 days each, while April, June, September and November consisted of 30 days each. The month February was taken to consist of 28 days, whereas, in the leap year, it would have 29 days. This calendar continued for 1600 years.

            Subsequently, an error of 10 days was defected in these calculations, because the earth actually takes 365.2422 days to complete one revolution round the sun, making a difference of 7.8 days over a period of 1000 years. In 1582, Pope Gregory XIII took a decision to drop ten days form the year 1582, and for future accuracy, he ordered that a leap ear should be skipped in the last year of every century unless it was divisible by 400. So 1700, 1800 and 1900 were not leap years, but the year 2000 was a leap year. With February having 29 days. This was called the Gregorian calendar and is in use all over the world, even today.

            The second calendar in use is the lunar calendar, which is based on time taken by the moon to complete one revolution around the earth, which is 29 ½ days. The lunar year consists of 354 days (29 ½ *12), which s less than the solar year by 11 days, and this makes a difference of 33 days every three years. This difference is resolved by having 13 months after every three lunar years.

            This additional one month is called Malmas in Hindi. To make up of the days of month, the actual numbering of the lunar days is advance or deferred for the necessary adjustment. On March 22, 1357, the government of India
introduced the shaka calendar based on the lunar system as the official calendar. The Shaka era is behind the Christian era by 78 years.

            In addition to these two calendars, some countries have other kinds of calendars also, which are used for the religious and other requirements of those countries.

            You have already read that while making the calendar, the 365 days of a normal year were divided into 12 months. These months have been named as January, February, March, April, May, June, July, august, September, October, November, and December. Do you know how they got these names? January is the first month of the year. Its name originated from Janus, the name of roman god. The roman thinks that this god has two faces- one for looking into the past and the other into the future.

            February is named after the roman festival februo.

            Mars was the roman god of war. March is named after him.

            April is probably derived form the Latin word aperire, which means to open. Since the spring season falls in this month and there is blossoming in trees and plants, this month has bee named April.

            The word may is derived from the roman goddess Maia’s name.

            The origin of June is not definitely known but probably this has been derived from the name of juno- the Queen of Heavens.

            July is named after Julius Caesar, who was born in this month. He was the first man who made significant contributions to the development of the modern calendar.

            August is named after Augustus Caesar of Rome, who had won many battles in this month.

            September finds its origin in the Latin word septem meaning seventh. This was the seventh month in the old Roman calendar.

            October comes form the roman word octo meaning eight. In the old Roman calendar, this was the eighth month.

            November originates from the Latin word novem meaning nine. This was the ninth month in the old Roman calendar.

            December is derived from the Latin word decem meaning tenth. This was the tenth month in the old Roman calendar.

The Wettest and Driest Places on Earth

Where are the wettest and driest places on earth?

            Have you ever wondered which the wettest and driest places on earth are?  Did you know that Cherrapunji, in India, holds the recorded for the highest rainfall in one month- 929.9 centimeters in July 1861? It also holds the highest rainfall recorded in a year-2646.1 centimeters, in 1861. Hawaii has the record of the maximum number of rainy days- 350 a year. It also has the highest average annual rainfall.

Earth’s Wettest Place Cherrapunji
Earth’s Driest PlaceThe Atacama Desert

            Cherrpunji clings to a hillside in Assam. It has dense rainforests. The Hawaiian mountains are in north-east of the earth. The average annual rainfall there is 1145.5 centimeters.

            Let us now see which place gets the least rainfall in the world. The driest place on earth is Atacama Desert in northern Chile. Here, the first rain in 400 years falls in 1971.

            The Atacama Desert is exceptionally dry. Sahara has an average rainfall of 2.8 centimeters a year, while Arabian Desert has 8.1 centimeters a year.

Boiling Mud Pools

Where does mud boil?

            Have you heard of boiling mud? It is very unusual. Boiling mud is one of the side effects of volcanic activity. Hot water and gases form beneath the surface bubble through the mud, as a result, it looks like a pan of boiling porridge.

Boiling Mud Pool

            Boiling mud can be seen in a number of volcanic areas of the world. Volcanic gases such as sulphur, which creates heat and causes the boiling effect, usually gives the mud a foul smell. On the other hand, the associated minerals are said to promote healing and thus, mud pools are of the used as health centers.

            The Italian island of volcano is visited for curing rheumatism. Many people visit pools and springs of the volcanic plateau in North Island, New Zealand, which are used as health centers for healing diseases.

            Boiling mud is still found in areas where volcanoes have bee inactive for hundreds of years, such in the West Indian island of St. Lucia. This proves that volcanic activity is still going on deep beneath the earth’s surface.

The World’s Hottest and Coldest Places

Where are the world’s hottest and coldest places?

            The Sahara desert in Libya is the hottest place in the world. The highest temperature was recorded in September 1922, and it was 58 degree centigrade. Death valley, California, in the USA, recorded its highest temperature of 56.7 degree centigrade in July 1913.
World’s Hottest Place Sahara Desert
World’s Coolest Place  Antarctica

            The highest temperature recorded in the Sahara desert is due to long periods of sunshine. In eastern Sahara, 4300 hours of sunshine has been recorded in a year- an average of 11 hours 47 minutes per day. This long period of sustained heat raises the temperature to a very high level.

            The death valley of California, where temperatures up to 50 degree centigrade are very common; this area also being a desert.

            Antarctica is the coldest place in the world. In July 1983, Russian scientists measured a very low temperature of -89.2 degree centigrade at Vostok, the Russian research station in Antarctic. In Siberia, the lowest temperature was -68 degree centigrade recorded in 1892.

Types of Climates

How many kinds of climate are there?

            Changes in the weather, both on a day-to day and seasonal basis have puzzled man for ages. Climate is the average weather experienced in a region over a period of years. Climate depends on many factors such as the average temperature, rainfall, atmospheric pressure, wind directions, location, height above sea level and latitude of the place.


            Different kinds of climate are found in different parts of the world. Various instruments like the thermometer, barometer, rain gauge, etc. are used to study the climate, atmospheric pressure, wind speed and directions, rainfall, clouds, humidity, etc.

            After much study, the world has been divided into 12 major climatic regions. For convenience, these climatic regions have been grouped into three on the basis of their latitudinal positions and extent. These are the low latitude climatic zone, the mid-latitude climatic zone and the high latitude climatic zone.

Low Latitude Climatic Zone: This zone lies close to the equator, generally between the tropic of cancer and the tropic of Capricorn. It includes the humid tropical region, trade wind coastal region, tropical desert and steppe, tropical monsoon and savannah regions. The temperature in this region is very is high. The annual rainfall is heavy over most of the region, especially in the tropical areas.

Mid-Latitude Climatic Zone: This includes china type, west European type, Mediterranean, mid-latitude desert and the steppe region. The summers are not very hot, but the winters are very cold.

High Latitude Climatic Zone: It includes Taiga type, Tundra type, ice cap and high mountain type regions. In these places, temperatures are very low during the winter and frigid even during the summer. They generally lie beyond the Arctic Circle and the Antarctic Circle.

The 12 major subdivisions of climate within the zones given above are---

1.        Tropical wet
2.       Tropical wet and dry
3.       Highlands
4.       Desert
5.        Steppe
6.       Subtropical
7.        Subtropical moist
8.       Oceanic moist
9.       Continental moist
10.  Sub-arctic
11.  Polar
12.  Ice cap

            Climate affects the type of houses we live in, the clothes we wear, the food we eat and the type of transportation we use. In short, it has a major effect on our lives.

We Don’t Feel the Earth’s Motion

Why don’t we feel the earth’s motion?

            Till a few hundred ears ago, it was believed that the earth was the centre of the universe and that the sun, the moon and the stars revolved round it. This belief was based on the assumption that the earth appears to be stationary, while the positions of the stars keep on changing. In 1545, Nicholas Copernicus, a polish astronomer suggested that the earth revolves around the sun. It was proved that the earth revolves around the sun and completes one revolution in 365 ¼ days. This period is called a year. Secondly, it also rotates on its own axis and takes 24 hours to complete one rotation.

Tidal Bulges from Moon and Sun

            If the earth is rotating and revolving at the same time, why don’t we feel its motion? The answer is that because of gravity, all the things situated on the earth including the atmosphere move with the earth and hence we cannot feel its motion. If you rotate a football with an ant on it, the ant will not feel that the ball is rotating.

            Exactly like the ant on the football, we are present on the surface of the earth and do not feel its movement.

            The biggest proof of the earth’s motion is the change in seasons. Seasons occur due to the earth’s revolution around the sun as well as due to its rotation on its own axis. Day and night are caused by the earth’s rotation on its axis. The portion of the earth which faces the sun experiences day, while the darker portion has night.

            If the earth did not rotate on its axis, the part of the earth facing the sun would always have day while the rest would have night forever. The earth’s axis makes an angle of 23 ½ degree with vertical. As a result of this, one pole faces the sun continuously for six months, and for the next six months, it does not. This explains the six-month duration of days and nights on the poles. All these observations confirm the motion of the earth round the sun, as well as on its own axis.

Friday, May 25, 2012

Inside the Earth

What is there inside the earth?

            Man has always bee curious to know as to what lies inside the earth. He tried digging and various other methods and finally, found an indirect method to know- through the study of earth quake vibrations or seismic waves. Studies reveal that our earth has three main layers- the outer surface on which we live is called the earth’s crust, below it is the mantle, and then comes the innermost part known s the core.

The internal structure of the earth

            The outer layer or the earth’s crust has two sub-layer-the first layer is the lighter one and is called Sima for silica-magnesium, while the second sub-layer is heavier than the first and is called Sial for (silica-aluminum). Thus, the earth’s crust is mainly composed of silica. Its depth varies form 16 kilometers to 50 kilometers on land and about 5 kilometers under the oceans. The volume of this crust is only 1% of the earth’s volume, while its weight is around 4% of the earth’s total weight. As we go deeper into the earth’s crust, the temperature increases.

            For every 35 meters in depth, there is an increase of about 1 degree centigrade in temperature. At a depth of 3 kilometers, the temperature is around 100 degree centigrade boiling point of water and at 50 kilometers; the temperature is 1,200 degree centigrade- hot enough to melt rocks.

            The second layer, which is below the crust, is called the mantle. It is 2,880 kilometers thick. It is mainly composed of silicon, magnesium and iron. The rocks in the mantle are denser than sial and sima. Its total volume is 84% of the earth’s volume. Its weight is around 67% of the earth’s weight.

            The innermost portion of the earth is called core which is made of high density solid materials. The core has two parts-outer core and inner cores. The outer core is liquid, and the inner core is solid. Its thickness is about 3482 kilometers. Its temperature is around 4800 degree centigrade. Its volume is 15% of that of the earth, while its weight is 32% of the earth’s weight. This solid core is surrounded form all sides by molten iron and nickel. Its temperature is around 3900 degree centigrade. The thickness of this molten mass is around 2.240 kilometers. The centre of the earth is some 6,336 kilometers form the earth’s surface.

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