What is the Big Bang Theory?

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The Big Bang theory explains the origin of the Universe. Scientists believe that the Universe was created about 15,000 million years ago in an explosion called the Big Bang. Matter was formed in the tremendous heat that followed and galaxies were created. It is believed that the Universe may expand for ever, or it may eventually stop expanding and then collapse inwards. It is predicted that before this, in about 5000 million years, the Sun will expand and burn the Earth.

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What is a Geostationary Orbit?

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Artificial satellites sent from the Earth orbit around the earth. The ones near the Earth orbit faster than the ones far away. A satellite 35,900 Km above the Earth's surface, takes 24 hours to orbit once. The satellite is always above the same point on the Earth's surface as the planet rotates. Geostationary orbit is also called as geosynchronous ' orbit. Such satellites are used to receive telephone and television signals and retransmit them over long distances.
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Why is Venus so Hot?

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T he planet Venus is named after the Roman goddess of beauty and love. It is the brightest planet in the Solar System. It is visible as a star. Venus is much hotter, because it is much closer to the Sun. The atmosphere there is 90 times thicker than that of the Earth and the surface is hidden in a white cloudy cloak. This thick atmosphere acts like a blanket which holds back the heat of the Sun and turns the midday temperature to 4800C. The atmosphere on Venus consists mainly of the carbon dioxide gas which acts as a greenhouse roof , trapping the Sun's heat. The rocks on Venus are hotter than boiling water. Above the rocks, winds blow at a speed of 320 km/hour .
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What is a Mouse?

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An input device that is used to point and select an option on the VDU is called a mouse. The basic features of a mouse are a flat-bottomed casing designed for gripping by one hand ; one or more buttons on the top; a multidirectional detection device (usually a ball) on the bottom; and a cable connecting the mouse to the computer. By moving the mouse on a surface (such as a desk top), the user typically controls an on-screen cursor . The user presses one of the mouse's buttons, producing a 'mouse click‘ to select items or choose commands.
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Why does Mistletoe Grow on Trees?

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M istletoe is a plant which grows on branches of higher trees. It is a partial parasite since it has green leaves containing chlorophyll and can make its own food by photosynthesis. It takes the water and minerals it needs from the sapwood of the host tree. It is found growing on trees like apple, hawthorn, willow, poplar and lime . The seeds of mistletoe are spread by birds and once the seed germinates on the host tree, it develops haustorium . The haustorium is a tough structure and ensures of a regular supply of water and nutrients from the sapwood of the host to the mistletoe. The plant then develops a clamp like structure on the tree to be placed firmly.
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When were the First Spinning Machines Invented?

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People in the olden days used to spin thread by hand . They pulled fibres out of cotton and wool and twisted them together into thread. Spinning machines were invented in Britain in the 1700s. These machines had rollers turning at different speeds to twist the fibres into yarn. James Hargreaves in 1764 produced the first successful spinning machine. It was the hand-powered jenny which produced thin yarn. Richard Arkwright's water frame of 1769, powered by water wheels, gave a sturdy thread. Samuel Crompton combined these two spinning machines in 1779 , to make the spinning mule, which could spin many kinds of yarn. These machines were the precursors of the Industrial Revolution . 
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