My Science School

The Moon is the nearest object to Earth in the Universe – an average of 238,900 miles (384,400km) away. Its distance varies slightly because it follows an egg-shaped (elliptical) orbit around the Earth.

When the Apollo astronauts visited the Moon, from 1969 to 1972, they left behind small ‘retro’reflectors’, rather like the reflectors on the back of a car. Astronomers on Earth shoot a powerful pulse of laser light at these retro-reflectors, and about two and a half seconds later their telescopes pick up a faint flash as the pulse of light returns to Earth. They then multiply the time it takes for the pulse to leave Earth and return, by the speed of the light, and divide the result by two to arrive at the Moon’s distance from Earth.

The Moon and the Earth are drawing apart because the friction between the Earth’s ocean floor and the water heaped up in the tides is gradually slowing its rotation. This is making it lose energy. In return, the bulges of the Earth’s ocean tides pull the Moon forward in its orbit, making it gain energy. The Moon is therefore gradually moving away from the Earth as it is pulled into a larger orbit.

 

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Circling around the Earth far out in space are giant cameras which can see details on the ground only 12in (300mm) across. The cameras are fixed to satellites as big as a single-Decker bus 50ft (15m) long, and take up half the area of the satellites as ‘spies in the sky’ to check the extent of other countries’ arsenals.

But satellite photography has other purposes. Every day, TV weather forecasts show pictures of the Earth photographed by cameras on board satellites. Geologists and economists study photographs taken from space that reveal rocks and crops on Earth. And astronomers look at distant stars and galaxies, unhindered by the Earth’s atmosphere. but how do these images reach Earth?

The most common way to send photographs from space is to use radio waves and beam the pictures down in the same way that TV pictures are sent. The amount of detail that you can see depends on the spacing between the lines that make up the picture: the more lines, the more detail you can make out.

The world’s most advanced commercial satellite for surveying the ground, the French SPOT satellite, transmits 6000 lines per picture – nearly ten times as many as the 625 lines used on most of the world’s TV sets. This means that in a picture which covers an area of 40sq miles (100 sq km) and taken from a height of 570 miles (920 km

), details as small as 30ft (10m) across are visible. In a photograph of the whole of Paris, for example, you could pick out the Arc de Triomphe.

Military intelligence experts generally want to be able to make out even finer detail. When monitoring a war, they need detailed photographs that will enable them to count the number of troops on a battlefield, or reveal different types of aircraft or ship.

The most modern American ‘spy satellites’. The KH-11 series, relay their pictures by television techniques. But, in general television images cannot show as much detail as a fine-grained 16mm or 35mm film. When film is used, it has to be returned to Earth physically. If the photographs are being taken in manned spacecrafts, the cosmonauts can bring the film back with them, but this is obviously impossible with unmanned spacecraft. So the Americans and the Russians – and more recently the Chinese – have developed satellites that return a film to Earth automatically.

The American ‘Big Bird’ satellites have perfected this technique. The exposed film is out into one of six re entry capsules, which is then jettisoned and drops back into the Earth’s atmosphere. as it parachutes down, the capsule is captured, or lassoed, in a wire loop which trails behind a C-130 Gercules transport plane.

 

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Stereophonic sound helps to give a sense of direction and feeling of depth to radio broadcasts or recordings. When you hear an orchestra playing on the radio, for example, you can tell where the violins, woodwind and drums are positioned.

Many  VHF radio programmes are now broadcast in stereophonic sound system pioneered in the United States by Zenith and General Electric in 1961. The program is recorded using a number of microphones, and edited to produce sounds from the right and left of the broadcast studio on two separate tracks.

The transmitter sends out two sets of radio signals over the air. One set carries the combined output of the microphones so that it can be received on ordinary (mono) receivers. The other set carries coded signals for a stereo receiver. It has a decoder that can sort out the coded set into left and right channel signals. These are amplified separately, and fed to separate left hand and right hand loudspeakers.

 

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Iron and its alloys, such as steel, are naturally magnetic. They draw other magnetic substances towards them if they are within a certain range, known as the magnetic field. All magnets have a north and south pole, and it is opposite poles that attract each other.

The magnets attractive power relies on the arrangement of its atoms. All the atoms are tiny magnets formed into groups, known as domains. The magnetic strength is increased if the domains are induced to fall into line by the action of another magnet.

A bar of iron placed inside a coil of wire carrying an electric current will be magnetised for as long as the current flows. This is because an electric current has a magnetic field that act at right angles to its direction of flow in the same way as naturally occurring electromagnetic radiation. The strength of the magnet depends on the strength of the current.

These electromagnet can be much stronger than ordinary magnets, and can easily be magnetised or demagnetised by switching the electric current on or off.

Conversely, moving a magnet in and out of a coil of wire will set up an electric current in the wire for as long as the magnet is moving. This was how the first electric generator was produced after the principle (electromagnetic induction) was discovered by an English man, Michael Faraday, in 1831.

 

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Miniaturized information storage will be a boon to such establishments as libraries who have to store great number of bulky books, newspapers and reports. At present, the British Museum adds an estimated 8 miles (13 km) of books to its library shelves every year.

Scientists at Cavendish laboratory, Cambridge, are used an electron beam to generate patterns of dots to form both microscopic pictures and lettering in aluminium fluoride. In this way they can reduce printed words to a density of 10 million words per square millimetre.

Since the beginning of electron-beam welding on an industrial scale at the end of the 1950s, countless electron-beam welders have been designed and are being used worldwide. These welders feature working vacuum chambers ranging from a few liters up to hundreds of cubic meters, with electron guns carrying power of up to 100 kW.

An electron microscope uses a controlled beam of electrons to illuminate a specimen and produce a magnified image. Two common types are the scanning electron microscope (SEM) and the transmission electron microscope (TEM).

 

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So it was only pure luck that Lovells calculation on the motions of Uranus and Neptune had led to the discovery of Pluto! Astronomers are now asking what else could be pulling on Uranus and Neptune. The answer seems to be a massive planet lying much farther out in the solar system.

Bob Harrington, of the US Naval Observatory, has calculated that this planet is currently in the southern part of the sky. Every few weeks, telescope in New Zealand, at the Black Birch Astrometric Observatory near Blenheim, takes photographs of Harrington’s suspect part of the sky.

Harrington has allies in his research that no previous planet hunter could call on space probes. If planet 10 is pulling on Uranus and Neptune, it should also disturb the parts of the three spacecraft - Pioneer 10, Pioneer 11 and Voyager 1 - that are currently leaving the solar system. Scientists are measuring theirs motions carefully, to see if planet 10 is pulling them off-course. So far, the results are negative.

Other astronomers are not convinced by the calculation made so far. They believe that planet 10 could be anywhere in the sky, and so they are taking a different approach. Planets produce copious amount of infrared radiation. In 1983, the infrared astronomical satellite scanned the whole sky, looking for objects in the universe that produce infrared radiation. If planet 10 exists, then the satellite will probably have picked it up. The results from this survey were recorded on 60 miles (100 km) of computer tape. Astronomers, using this vast amount of data, have located many interesting objects comets, asteroids and newborn stars but planet 10 has still to come to light.

 

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On April 12, 1981, the 1st to space shuttle, Columbia, lifted off from Cape Canaveral on its maiden flight into space. Columbia was powered by three liquid fuelled engines and a pair of giant strap on, solid fuel boosters, and was controlled by five sophisticated, interlinked computers. But despite the space shuttles apparent complexity, the basic principle that makes it work is exactly the same as that behind a simple firework rocket or a balloon that zooms across the room when you let go of its neck. It is a principle of action and reaction.

In the 17th century, the English physics to Sir Isaac newton summed up one of the basic rules of the universe in the statement: ‘action and reaction are equal and opposite’. For example, when the neck of an inflated balloon is released, and air rushes out through the aperture, the equal and opposite reaction to the escaping rush of air pushes the balloon forward.

Unlike a balloon, a rocket does not contain compressed gas. Instead, it manufactures gas by burning solid or liquid fuels. But once the gas has been produced, the principle is the same. As the hot exhaust gases escape from its rear, the rocket is pushed forward in an equal and opposite reaction to the rush of escaping gases. But, unlike a balloon, which darts in all directions, the rocket is designed to keep a stable course.

Colombia’s three liquefied fuelled engines, which together burn 100 tons of fuel a minute, produce a downward stream of gases that cause an opposite, upward force or reaction 640 tons. The gases from two solid fuel boosters produce a reaction of 2400 tons. The total upward reaction on the shuttle is therefore more than 3000 tons. But the few fully fuelled shuttle weighs only 2000 tons, so the reaction is sufficient to lift it off the ground and the accelerate it towards space. Once in space, the shuttle goes into its regulated orbit around the earth.

 

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Each of the two Voyager craft gets its electrical power from a miniature nuclear generator, which consists of three metal cylinders, each 17in (430mm) long and 13in(330mm) wide, connected end to end. The cylinders are packed with plutonium dioxide, a radioactive substance.

Surrounding the core of each cylinders are hundreds of thermocouples. There are miniature electric circuits, consisting of a piece of silicon and a piece of germanium. One end of each thermocouple is heated by the decaying plutonium; the other faces outwards into the cold of space.

The difference in temperature between the two ends of the thermocouple causes an electrical current to flow through it. When electron in the silicon are distributed by heating, free electrons will tend to move to the germanium, creating a current.

When each Voyager was launched, in 1977, the three cylinders together produced 475 watts of electric power. But the power decreases by 7 watts per year, as the plutonium decays.

 

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Most of the Earth’s water (around 97%), is contained in the oceans. The polar ice caps hold a further 2%. The remainder (just 1%) is continually recycled through a natural process called the water cycle. The heat of the Sun evaporates water from the sea, lakes and rivers. This produces water vapour, which is held in warm air in the atmosphere. When the vapour moves to a cool area it condenses, forming clouds, and eventually falls to the surface as rain, hail or snow. This waters the land and feeds the world’s water supplies. Most of the water then returns to the oceans, and the cycle continues.

Evaporation, one of the major processes in the cycle, is the transfer of water from the surface of the Earth to the atmosphere. By evaporation, water in the liquid is transferred to the gaseous, or vapour, state. This transfer occurs when some molecules in water mass have attained sufficient kinetic energy to eject themselves from the water surface. The main factors affecting evaporation are temperature, humidity, wind speed, and solar radiation. The direct measurement of evaporation, though desirable, is difficult and possible only at point locations. The principal source of water vapour is the oceans, but evaporation also occurs in soils, snow, and ice. Evaporation from snow and ice, the direct conversion from solid to vapour, is known as sublimation. Transpiration is the evaporation of water through minute pores, or stomata, in the leaves of plants. For practical purposes, transpiration and the evaporation from all water, soils, snow, ice, vegetation, and other surfaces are lumped together and called evapotranspiration, or total evaporation.

Water vapour is the primary form of atmospheric moisture. Although its storage in the atmosphere is comparatively small, water vapour is extremely important in forming the moisture supply for dew, frost, fog, clouds, and precipitation. Practically all water vapour in the atmosphere is confined to the troposphere (the region below 6 to 8 miles [10 to 13 km] altitude).

The transition process from the vapour state to the liquid state is called condensation. Condensation may take place as soon as the air contains more water vapour than it can receive from a free water surface through evaporation at the prevailing temperature. This condition occurs as the consequence of either cooling or the mixing of air masses of different temperatures. By condensation, water vapour in the atmosphere is released to form precipitation.

Precipitation that falls to the Earth is distributed in four main ways: some is returned to the atmosphere by evaporation, some may be intercepted by vegetation and then evaporated from the surface of leaves, some percolate into the soil by infiltration, and the remainder flows directly as surface runoff into the sea. Some of the infiltrated precipitation may later percolate into streams as groundwater runoff. Direct measurement of runoff is made by stream gauges and plotted against time on hydrographs.

Most groundwater is derived from precipitation that has percolate through the soil. Groundwater flow rates, compared with those of surface water, are very slow and variable, ranging from a few millimetres to a few metres a day. Groundwater movement is studied by tracer techniques and remote sensing.

Ice also plays a role in the water cycle. Ice and snow on the Earth’s surface occur in various forms such as frost, sea ice, and glacier ice. When soil moisture freezes, ice also occurs beneath the Earth’s surface, forming permafrost in tundra climates. About 18,000 years ago glaciers and ice caps covered approximately one-third of the Earth’s land surface. Today about 12 percent of the land surface remains covered by ice masses.

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Mineral water comes from natural sources of water beneath the ground. The types of minerals in the water will depend on the type of rock over which the water has been running —different areas produce mineral water containing different types of minerals. Calcium, sodium and sulphur are examples of minerals commonly found in mineral water. Sources of mineral water are most often in mountainous and hilly regions.

Although water covers three quarters of the world and adorns the skies in its gaseous form, the truth is water fit for human consumption is growing scarce. We all must take care to conserve and care for it as we do our greatest treasure: life.

Nevertheless, nature gives us a very special kind of water from the depths of the earth, one that has been enriched with the earth’s minerals and naturally purified through filtering during its journey underground.

Mineral water is water from a mineral source that contains various minerals, such as salts and sulfur compounds. Mineral water may be effervescent (i.e., “sparkling”) due to contained gases.

Traditionally, mineral waters were used or consumed at their sources. This was often referred to as “taking the waters” or “taking the cure.” Civilization eventually developed around these sources, and people used them for spas, baths, or wells. The term “spa” was a place where the water was used for soaking; “bath,” where the water was used primarily for bathing, therapeutics, or recreation; and “well,” where the water was to be consumed.

Mineral water comes from natural sources like wells, pure and rich in minerals. Unlike tap water that receives different treatments before human consumption, mineral water is bottled directly from the source, without adding any chemical elements. It only goes through a physical process of filtration to ensure maximum purity.

• Mineral waters can be classified according to their origin:


• Meteorological: Produced by rain, snow, and de-icing.


• Juvenile: Those that see daylight when surfacing.


• Fossil: Formed from sediments deposited on the sea floor.


• Mixed: Composed from a mixture of meteorological, juvenile, and fossil water.

Today it is far more common for mineral water to be bottled at the source for distributed consumption. Traveling to the mineral water site for direct access to the water is rare, and in many cases not possible because of exclusive commercial ownership rights. There are more than 3,000 brands of mineral water commercially available worldwide.

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Many millions of people in developing countries do not have access to clean drinking water and sanitation. In the countryside, people may be forced to use the same ponds, streams, rivers and lakes for drinking and for sewage. In cities, water supply and sewage systems are often inadequate and, in both cases, people may be exposed to serious illnesses such as malaria, cholera and yellow fever.

The United States has one of the safest public drinking water supplies in the world. Over 286 million Americans get their tap water from a community water system. The US Environmental Protection Agency (EPA) regulates drinking water quality in public water systems and sets maximum concentration levels for water chemicals and pollutants.

Sources of drinking water are subject to contamination and require appropriate treatment to remove disease-causing contaminants. Contamination of drinking water supplies can occur in the source water as well as in the distribution system after water treatment has already occurred. There are many sources of water contamination, including naturally occurring chemicals and minerals (for example, arsenic, radon, and uranium), local land use practices (fertilizers, pesticides, and concentrated feeding operations), manufacturing processes, and sewer overflows or wastewater releases.

The presence of contaminants in water can lead to adverse health effects, including gastrointestinal illness, reproductive problems, and neurological disorders. Infants, young children, pregnant women, the elderly, and people whose immune systems are compromised because of AIDS, chemotherapy, or transplant medications, may be especially susceptible to illness from some contaminants.

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In parts of the world that receive little rainfall, access to water can be difficult. In such areas, wells May be dug deep underground, or water can he piped from natural springs. Some countries even process seawater at a desalination plant. The seawater is heated, and only pure water evaporates. When it condenses, it is collected, leaving behind the salt in a concentrated form.

It has been the driest start to a summer in over 45 years in the UK. Yet, much of the country had water in reserve when it began, ensuring a continued safe supply for drinking and washing. Millions around the world are not that lucky: despite high rainfall, they go thirsty.

In some of the wettest countries in the world - where rainy days bring a lot more water than the 1248mm average that falls yearly in the UK, according to World Bank data - clean water is extremely hard to get, especially for those living in poverty.

Unlike the UK where it rains all year round, many of these countries face heavy rainfall in one season and severe drought in the next - both exacerbated by climate change - putting water resources under heavy strain.

In some regions, climate change is making water sources increasingly unreliable as flooding contaminates previously drinkable water. Yet, the problem is often not a physical lack of water: some places have significant underground reserves - known as 'groundwater' - because of abundant rainfall. Here, thirsty communities cannot get sufficient clean water because of a lack of investment in the infrastructure needed to deliver a reliable supply, indicating a lack of political prioritization.

"Not having clean water to drink is not, for most people, due to a lack of rain. For the one in nine people around the world - 844 million - who do not have clean water close to home it is usually because there is not enough investment in systems to ensure rainwater is captured, stored, treated and piped effectively."

Papua New Guinea. The impacts of climate change - rising seas and extreme weather - have tainted groundwater, meaning that even though an average of 3055mm of rain falls each year, most of the water is unsafe to drink. The number of people with access to clean water close to home is decreasing: 4.83 million people (or 63 percent of the population) do not have clean water available within a half hour trip.

Sierra Leone. Sierra Leone is twice as wet as the UK with 2427mm of rain on average each year, yet, 4 out of 10 people (42%) lack basic access to clean water. The Ebola outbreak was aided by a lack of clean water as health centres and communities struggled to maintain the high hygiene standards needed to halt the spread of the virus.

Liberia. High on the list of the world’s wettest countries with 2421mm of rainfall on average each year, a third of the population remains without access to clean water, or 1.36 million people. Liberia is still recovering from two devastating civil wars that wiped out much of the country's infrastructure and the 2014 Ebola outbreak demonstrates the urgency to rebuild. 8 in 10 people don't have toilets and go out in the open, risking contaminating water sources, many of which are already at risk from industrial and mining pollution.

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Harmful bacteria that may cause serious diseases and death need to be removed from water before it can be used for domestic purposes. Dirt particles are removed because they can wear away pipes or damage industrial equipment.

Water purification, process by which undesired chemical compounds, organic and inorganic materials, and biological contaminants are removed from water. That process also includes distillation (the conversion of a liquid into vapour to condense it back to liquid form) and deionization (ion removal through the extraction of dissolved salts). One major purpose of water purification is to provide clean drinking water. Water purification also meets the needs of medical, pharmacological, chemical, and industrial applications for clean and potable water. The purification procedure reduces the concentration of contaminants such as suspended particles, parasites, bacteria, algae, viruses, and fungi. Water purification takes place on scales from the large (e.g., for an entire city) to the small (e.g., for individual households).

Most communities rely on natural bodies of water as intake sources for water purification and for day-to-day use. In general, these resources can be classified as groundwater or surface water and commonly include underground aquifers, creeks, streams, rivers, and lakes. With recent technological advancements, oceans and saltwater seas have also been used as alternative water sources for drinking and domestic use.

Clean water is essential for every human being, for drinking, cooking and other daily uses purposes like bathing, brushing, washing clothes etc. It not just makes our life healthier but also fulfills the hygiene purpose.

The regular tap water being supplied in your home might seem clear but possess various sorts of health-affecting bacteria and viruses such as fluorine compounds, chlorine, mercury, lead, pesticides and other types of waste particles.

And its consumption can lead to serious health issues, and sometimes the result can be massively harmful. As per the research contaminated water lead the diseases like- diarrhea, cholera, dysentery, typhoid, and polio, and is estimated to cause 502 000 diarrhea deaths each year.

Water is a limited resource which is chemically treated to obviate various types of harmful viruses or bacteria available in it, that makes approx. 1.1 million ill each year (according to the research) and this is the core reason why water purification is necessary. Since your family’s health is in your hand, you must be very careful with the kind of water they are consuming for their day to day uses.

Several sorts of chemicals and viruses in unfiltered water can increase the chances of some kind of cancer risks. Thus, eliminating these chemicals can help you get rid of such cancer risks. Besides that, pure water also keeps things moving in your digestive tract. It helps to push food through and get you healthy digestion.

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All living things depend upon water for their survival; life on Earth would not exist without it. A clean supply of water is essential for people, not only to drink but for sanitation and health reasons. There is plenty of water on Earth, but not everyone has access to the same amount. Demand for water is always increasing, and supplies in many parts of the world are overstretched. In such areas, supplying fresh water can be a time-consuming and expensive business. For many people, a safe, regular supply of water is taken for granted but without it life, and indeed industry, would come to a halt.

Water is a life giver - even a life creator. It lies at the basis of our understanding of how life works. It also lies at the basis of how we understand our own personal lives. Of the four (or five) basic building blocks of life, water is the only one with a visible cycle, which we call the hydrologic cycle. Fire has no cycle that we can see, either do earth or air. And we don't understand spirit (the ether) enough to know if it does or not. Water is a constant reminder that life repeats.

The hydrologic cycle works as follows: From its most usable state, water evaporates and joins the air as water vapor. When the air cools, the vapor condenses and creates clouds, which help block heat from the sun. Colonies of the ice-nucleating bacterium, P. syringe, blown into the clouds by wind, help them to precipitate and fall as rain, snow, or hail. Much of the precipitation is stored on land as groundwater and lakes, snow and ice. From there water flows to the sea, where it joins the "primordial soup" again as ocean, ready to start the cycle anew.

Here are many of the roles that water provides both for the earth and for humans—that help produce the abundance of life we see around us every day. Without even one of these our lives would be far different.

Without water the air and earth would vacillate between extreme hot and extreme cold every day, everywhere, with a gradual increase in temperature as time goes on. Part of the problem with global warming could be that we are using up too much land water and throwing rain away into the sea.

In addition to being the soup from which life emerged, the ocean and other water bodies act as home for more life than what lives on land. Mammals, fish, birds, insects, trees, plants, algae, krill, and many other forms of life either live directly in water or are wholly dependent upon it for survival. This includes the tiny iceworms, copepods, and diatoms that inhabit trillions of minuscule tunnels in icebergs and their undersides, providing food for whales and fish that migrate to the poles to eat.

Water and carbon dioxide are the two key components of plant photosynthesis, which is how plants make their food. Bees use water to make honey, flowers use water to make nectar, trees use water to make pitch, spiders and snakes use water to make venom, and termites mix saliva with mud to make their homes. Humans use water to make paint, dyes, inks, all kinds of drinks, and we bottle it straight. We use it for paper, fabrics, food processing, chemical compounds, and the manufacture of hundreds of other products essential to modern living.

Without water, plants and many insects and arthropods could not survive, nor would humans have developed the foods and industries we have.

To humans, as creators of our own lives, water is our servant. We use it to grow crops and livestock, to cleanse and keep ourselves healthy, to stimulate ideas for products, and to transport those products. We use its cycles to remind us that our own lives also work in cycles.

But if we abuse water, like masters have a tendency to do with servants, if we don't care for it and preserve it, we will end up destroying ourselves. We need the rain forests, the swamplands, the open rivers and lakes, the estuaries, icebergs, snow tops—water in all its natural forms we need. And so does the rest of life.

If, instead of commanding it, we could conceive of ourselves as a partner or an intelligent component of water's own rain and storage cycle, it might encourage us to be more respectful of what water can do and more careful of the way we utilize it.

With water, we thrive. Without water, there is no life. We must learn to value, conserve, and take care of the water we have.

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