THE POWER OF NUCLEAR

Nuclear power is produced by controlled (i.e., non-explosive) nuclear reactions. Commercial and utility plants currently use nuclear fission reactions to heat water to produce steam, which is then used to generate electricity.In 2009, 13-14% of the world's electricity came from nuclear power. Also, more than 150 naval vessels using nuclear propulsion have been built.

Nuclear reactor technology

Just as many conventional thermal power stations generate electricity by harnessing the thermal energy released from burning fossil fuels, nuclear power plants convert the energy released from the nucleus of an atom, typically via nuclear fission.

When a relatively large fissile atomic nucleus (usually uranium-235 or plutonium-239) absorbs a neutron, a fission of the atom often results. Fission splits the atom into two or more smaller nuclei with kinetic energy (known as fission products) and also releases gamma radiation and free neutrons.^[35] A portion of these neutrons may later be absorbed by other fissile atoms and create more fissions, which release more neutrons, and so on.

This nuclear chain reaction can be controlled by using neutron poisons and neutron moderators to change the portion of neutrons that will go on to cause more fissions. Nuclear reactors generally have automatic and manual systems to shut the fission reaction down if unsafe conditions are detected.A cooling system removes heat from the reactor core and transports it to another area of the plant, where the thermal energy can be harnessed to produce electricity or to do other useful work. Typically the hot coolant will be used as a heat source for a boiler, and the pressurized steam from that boiler will power one or more steam turbine driven electrical generators^.

UFO AND IT MYSTERY

A UFO is an Unidentified Flying Object.

Since man first started looking up into the skies he saw things he couldn't explain. For the last fifty years or so these things have taken on the label "UFOs." Originally an abbreviation for the Air Force term "Unidentified Flying Object", it has become a synonym to most people for "Alien Spaceship." For the Air Force, though, it is simply a term to refer to something in the skies that the observer can see but not recognize. It is "Something seen in the sky (or on the land, or exceptionally in the water, but thought capable of flight) which the witness could not identify and thought sufficiently strange to report to either an official or unofficial investigating body".

A UFO is the stimulus for a UFO report made by a UFO witness. UFO researchers (often called UFOlogists) study UFO reports and witnesses. UFO researchers cannot directly study UFOs. There are some reports in the literature of different governments recovering craft thought to cause UFO reports, but most of these reports are speculative. The study of UFO reports is referred to as UFOlogy. This implies a scientific basis to the study, when in practice very little scientific research is carried out. After careful investigation about 90% of all UFO reports can be reasonably explained as either natural phenomena or misidentification of normal manmade devices. Sometimes the term IFO is used for these Identified Flying Objects. Those cases which are identified as natural phenomena are often rare or short lived and are worthy of study in their own right.

In the early days of investigation used interchangeably with the term 'Flying Saucer'. More recently the term Flying Saucer has fallen into disuse, although some researchers use it as a term to specifically refer to an extraterrestrial spacecraft.

THE GREAT MILKY WAY

The Milky Way is the galaxy which is the home of our Solar System together with at least 200 billion other stars (more recent estimates have given numbers around 400 billion) and their planets, and thousands of clusters and nebulae, including at least almost all objects of Messier's catalog which are not galaxies on their own (one might consider two globular clusters as possible exceptions, as probably they are just being, or have recently been, incorporated or imported into our Galaxy from dwarf galaxies which are currently in close encounters with the Milky Way: M54 from SagDEG, and possibly M79 from the Canis Major Dwarf). See our Messier Objects in the Milky Way page, where details are given for each object to which part of our Galaxy it is related. All the objects in the Milky Way Galaxy orbit their common center of mass, called the Galactic Center (see below).




As a galaxy, the Milky Way is actually a giant, as its mass is probably between 750 billion and one trillion solar masses, and its diameter is about 100,000 light years. Radio astronomial investigations of the distribution of hydrogen clouds have revealed that the Milky Way is a spiral galaxy of Hubble type Sb or Sc. Therefore, our galaxy has both a pronounced disk component exhibiting a spiral structure, and a prominent nuclear reagion which is part of a notable bulge/halo component. Decade-long observations have brought up more and more evidence that the Milky Way may also have a bar structure (so that it would be type SB), so that it may look like M61 or M83, and is perhaps best classified as SABbc. Recent investigations have brought up support for the assumption that the Milky Way may even have a pronounced central bar like barred spiral galaxies M58, M91, M95, or M109, and thus be of Hubble type SBb or SBc.

ALL ABOUT OUR EARTH

our Earth

Earth is the third planet from the Sun. It is the first planet from the Sun to have a moon, a common feature of all of the other planets beyond our orbit. The Earths atmosphere reaches to approximately 80km above the surface, but this is only about one hundredth of the planets radius, and so occupies a relatively thin band around the planet. It is composed mainly of nitrogen (78%) and oxygen (21%), with the remainder built up from small traces of other gases. These relative proportions remain fairly constant up to around 80km, but the heavy gases become rare at greater heights and only hydrogen and helium are found in the outermost regions. At the height of the stratosphere, there is a concentrated layer of ozone, at about 25km. This ozone layer is vital to life on the planet, as it stops nearly all of the Suns harmful ultraviolet radiation from reaching the surface.

Atmosphere & Surface The Earth's atmosphere also contains a large amount of water vapour, although its concentration varies in different places, and is subject to seasonal variations. Most of it is visible as clouds, and most of these extend only to the top of the troposphere - up to 13km. It is in this region that the dominant weather systems are found. Above this lies a layer of warm air which holds cooler air below containing most of the water vapour, and the clouds that we see.

The surface of the planet is subject to much geological activity, and is shaped by continental drifting (plate tectonics). This makes the planet's surface relatively young, and taken in conjunction with other factors, such as the existence of an atmosphere and weathering, explains why few visible impact craters are to be found. The surface of the moon, which is heavily cratered, gives a more accurate a more accurate guide as to the quantity of collisions with debris making its way through the solar system. Here, the surface features date back to the formation of the solar system, and have remained undisturbed due to the moon's geological inactivity.

the Moon

The Moon is the Earth's sole companion, orbiting at an average distance of 384,400km. It follows us on our path around the Sun, making one orbit of us (as seen against the background of stars) every 27 days, 7 hours, 43 minutes. This period is referred to as the sidereal month. The Moon's equatorial diameter measures 3,476km making it less than one third the diameter of the Earth. The tides in the Earth-Moon system have slowed the Moon's rotation and locked it to Earth, this is tidal coupling and occurs throughout the Solar System.

Fleeting Eclipses As the orbital plane of the Moon lies within 5 deg of the apparent orbit of the Sun as seen from Earth, occasionally their positions in the sky coincide, giving rise to a solar eclipse.

At other times the Moon's orbit takes it into the shadow cast by the Earth into space, causing a lunar eclipse. Unlike solar eclipses, Lunar eclipses are readily observed from large areas of the Earth's surface, due to the greater extent of the Earth's shadow than that of the Moon's.

Changing Shape As we see the Moon only in reflected light, it shows distinct phases, depending on the angle made between itself, the Sun and the Earth, as the diagram shows.

At New Moon (1), all three bodies are aligned, with the Moon between the Earth and the Sun. During this phase, despite the absence of direct illumination by the Sun, the lunar surface is just visible in light reflected from the Earth. Full Moon (5) occurs when the Earth lies directly between the Sun and the Moon, with first (3) and last (7) quarters occurring at the 90 deg and 270 deg positions. The time taken from New Moon to New Moon, called the synodic month, is 29 days, 12 hours, 44 minutes.

ALL ABOUT SUN

The Sun is the most massive body in the Solar System, and provides two essential things without which life would not have developed, and could not exist: light and heat. It is our star, and is only significant because we are so much closer to it than the other 2 billion odd stars in the Galaxy.

Composition It is a great ball of searingly-hot gas, 860,000 miles in diameter (109 times the diameter of the earth), held together by its own gravity. It is roughly 75% hydrogen, 25% helium, with a tiny fraction of heavier elements. The temperature at the surface is over 6,000 degC, hot enough to vaporise iron. Inside, it is a different story. At its core, temperatures soar to over 10 million degC. This causes the nuclei of hydrogen atoms to fuse to form helium - a process known as nuclear fusion. As a result of this process, heat is released in vast quantities - driving the process of fusion in other atoms. Every second, 1038 reactions occur, destroying 5 million tonnes of matter. This huge release of energy prevents the star from collapsing under its own gravity.

Einstein in Action Despite the gargantuan number of reactions, and loss of mass (behaving according to Einstein & Rsquos famous equation: E=mc2), the Sun will continue much as it is for another 5 billion years. At the end of this time, the hydrogen in its core will be exhausted. However, the layer of helium that will have built up over the aeons will begin fusing to form even heavier elements, causing the star to swell in size to beyond the orbit of mars; destroying all the inner planets in the process. It will have become a red giant, but its surface temperature will have fallen to a mere 2,000 degC.

The Solar Spectrum Newton discovered that the Einstein & Rsquos light is not pure, but is made up of all the colours of the rainbow. Years later, it was discovered that not all the colours seem to be there!

If you produce the spectrum carefully, you will see thousands of black lines, knows as Fraunhofer absorption lines. These give away the presence of chemicals in the Sun, and that's how we know so much about it.

Under Study The Sun has been under study for years, but not until late 1995 did major discoveries start to be made with the launch of the joint NASA/ESA probe, SOHO. In April 1998, the British built and operated CDS spectrometer on board discovered tornadoes wider than Africa! The Sun has even been seen to have regular quakes. In June 1998, SOHO observed two comets crash into the Sun in quick succession.

End in Fire Red giants are smaller versions of red supergiants, like the star Betelgeuse. After a mere few million years, the Sun will expel its outer layers until only a small, but dense, core remains: it will have become a white dwarf. In size, it will be no bigger than the earth is today; but its density on earth would make a teaspoonful would weigh over 15 tonnes!