A discussion on solar sails on the television often implies the umbrella-like stretched surfaces around the satellites or the International Space Station (ISS). These are solar plants, which provide energy to the objects in space flight. Strictly speaking, the solar sail is a new technology, which uses the pressure of the solar radiation to drive the space probes.
Like the ‘solar sail’, the magnetic sail is also a new possibility for using the solar energy to power spaceships or space probes. This would become possible through the solar wind, a stream of electrically charged particles, coming from the sun. However, this method is still under research.
There are a lot of strong forces in the nuclei of atoms, which keep the particles together. There are two ways to release the energy hidden in the atomic nuclei. We can fuse them with one another, as occurs in the core of the stars, or we can split them, which is done in at nuclear power plants. To split an atom to release energy, a chain reaction is required in a reactor. Many people consider the atomic power plants also called nuclear power plants dangerous because radioactive material is released in this process.
Atoms are made up of a nucleus and a shell of electrons. The nucleus contains protons and neutrons. The protons are positively charged and repel each other like magnetic poles. At the same time, there is also a strong force of attraction, the nuclear force. This force prevents the nuclei from flying apart. The origin of this force is complicated and nuclear physicists have been studying this phenomenon.
Radioactivity is a property of the atomic nuclei to decay and thereby release radiation. Many atoms split when they are bombarded with neutrons, and others decay spontaneously. In both the cases, the radiation of radioactive material takes place. This radiation occurs in three forms. The alpha rays can reach only up to a few centimetres. The beta rays are made of electrons resulting from the splitting of atomic nuclei. They can go up to 1m and are stopped by metallic foils. The gamma rays are bundled energy released in the decay and are very dangerous. Even thick lead plates can only partly stop them. They can penetrate the cells of our body and can modify or destroy them.
Chain reactions are modifications in the composition of the atomic nucleus. The nucleus of a uranium atom, for instance, can be split by bombarding with neutrons. A lot of energy is released in the process. The fragments that arise as a result of the initial reaction fly off at a high speed and collide with the neighbouring nuclei, which get split in turn. The whole process takes place as long as the present mass of uranium is split. An enormous amount of heat is released when several nuclei are split at once. This can lead to explosions. For this reason, this chain reaction is initiated in a controlled way in nuclear power plants.
In atomic power plants - APP in short - the chain reaction of the uranium decay is allowed to run in a controlled way. The uranium rods in the reactor, which are bombarded with neutrons, are dipped in water, which slows down the neutrons and helps achieve a controlled nuclear fission. In addition, the fuel rods heat up the water to about 330°C. This heat is transferred in a heat exchanger to a second, non-radioactive water circulation, where the hot water evaporates and drives steam turbines. The energy is converted into electricity by means of the connected generators similar to other power plants.
Nuclear energy is a clean energy source as it does not produce any waste gases that pollute the environment. It is available in abundance on the Earth, but is still considered dangerous. People are afraid of an MCA (‘maximum credible accident’ or a worst – case scenario), something like Fukushima nuclear accident in Japan in March 2011 and Chernobyl in Ukraine in 1986. In both cases, the chain reaction went out of control and resulted in explosion. As a result, hazardous fission products were released in the air exposing people to harmful radiations. Problems are also faced in the normal operation, but precautions are taken to avoid any mishap. The used up fuel rods must be treated or stored at a secure place.
We need to manage our natural resources very carefully to ensure that the Earth remains in a habitable condition for future generations. We must preserve the greatest treasure of the Earth, the nature. Water should be judiciously used in regions where it is scarce. After all, in many parts of the world, people are still fighting for this valuable commodity. We need to make sure that we use non-renewable natural resources like coal, petroleum sparingly and use renewable resources like wind and solar energy more for our daily needs. A research to develop a harmonious way of living is very important for our future.
The term ‘resource’ is derived from French and means ‘tools’. Natural resources are the raw materials and the sources of energy present on the Earth. They include the deposits of coal, crude oil, or natural gas. The basic needs of our existence such as air, water, and soil, which gives us food, also belong to resources that we may be able to exploit in future. In economics, resource also means workforce and money.
Nature is an immense treasure that provides us with everything we need for our survival - clean air, fresh water, cultivable lands as well as plants and animals, with which we share this planet. Like all the living organisms, we too can use the nature, but we must always be careful. If the sensitive equilibrium of plants, animals, and water is disturbed, it can lead to grave problems, such as the threatening environmental pollution. We need to remember that nature is not indestructible. After a certain amount of destruction, it can no longer ‘heal’ itself.
For us, water coming out of the tap is a fact that we take for granted, but for many people across the world it is an absolute rare commodity. A large part of mankind does not have access to clean drinking water. This is a good reason to fight for water. In many areas of Africa, especially the dry areas of northern Africa, lack of rainfall can lead to a famine which leads to water hoarding. Although scientists predict that in future water will become one of the most hard-fought resources, the fight for water has already started. Many countries across the world are constantly at loggerheads regarding the right to water of a river flowing across the border.
There are many types of quality seals, for example, the bio-seal for food items which are grown ‘biologically’, which means without the use of chemicals. The Fair-Trade seal is often found on coffee or cocoa. Fair-Trade implies that people involved in the production of these products have also received an appropriate share of the profit. The FSC-logo marks the wood coming from forests, which are not damaged by cutting the wood. By purchasing the products marked with quality seals, we can support the idea of handling nature with care. We can help protect the environment by buying products with quality seals.
Polar lights, or aurora, are bright bands of light that streak in the sky of the polar regions. The sun emits high-energy ion particles. These electrically charged particles, also known as solar wind, get deflected by the Earth’s magnetic field. As a result they are drawn magnetically down into the ionosphere above the Earth’s surface at the poles. Their collision with the gas particles of the air causes the impressive display of colour in the northern sky. The magnetic field of the Earth protects us from the solar wind, which would otherwise destroy all life on the Earth.
In the Earth’s core, a viscous mass containing iron moves around a solid iron core. According to scientists, this flow of iron acts like an electrical coil and is the cause of the Earth’s magnetic field. Like any other magnet the Earth has a north pole and a south pole. These poles lay some thousands of kilometres away from the geographical poles. Not only sailors and pilots but also many migratory birds, dolphins, and salmons orient themselves to the magnetic field of the Earth. Small crystals of magnetite in their heads, acting like tiny compass needles, impart them a ‘magnetic sense’.