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Saturday, March 22, 2008

Why don’t we see the Moon on some Nights?

There are several reasons why we do not see the Moon on some nights. The moon does not give out its own light but reflects light from the Sun. Therefore, when the Earth comes between the Sun and the Moon. It casts a shadow over the Moon. This is known as an eclipse. When the Moon moves between the Earth and the Sun only its far side is lit by the Sun’s rays. The side facing Earth is in total darkness. We call this a ‘new’ Moon. Finally, on nights when the sky is over cast, the clouds hide the moon from us.

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Friday, March 21, 2008

Where do budgerigars live in the wild?

The parakeets are a widespread group of small old World parrots. Best Known is the Grass Parakeet or Budgerigar which is popular as a cage bird in so many homes. Budgerigars come from Australia. Large, chattering flocks feed among the grasses of the wide, inland plains. They eat the seeds of a variety of grasses, the fresh shoots of plants and any small insects they may discover while foraging. If you keep a budgie, do not be surprised if its snaps at a fly or other insects, for it is merely supplementing its diet like its wild relatives. Wild budgerigars are predominantly grass green in color with yellow head and blue tails. They make a spectacular sight as they flock each morning and evening to drink at a waterhole.

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Which tree’s berries are used to flavor gin and can be used in cookery?

The juniper. This evergreen tree is small and resembles a gorse bush with its spiky needles and fragrant grey bark. Juniper wood is used for small decorative carving and inlay, but it is the berries which make it useful. These are distilled into oil of juniper, which is then used in perfumery and exotic cookery. Another of its uses was in medicine, but nowadays its main function is to flavor gin.

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Sunday, March 16, 2008

Does a comet foretell disaster?

Before we can answer this question, we must look at exactly what a comet is. As you probably know, a comet looks rather like a star with a long, milky ‘tail’ stretching across the sky. In fact these ‘ tails’ are not tails at all because they always point away from the Sun and do not trail behind.

A comet seems to be made up of three main parts. The nucleus in the center of the star-like part is composed mainly of ice and dust particles, surrounded by a coma of much smaller particles and gas. The coma results from the melting of the ice and other substances as the comet approaches the Sun on it’s extremely stretched out elliptical orbit. The Sun’s radiation also tends to force some of these tiny pieces of ice away from the comet and out into space, which explains why the tail is always directed away from the Sun.

A Scientist called Halley, after whom a particularly bright comet is named, discovered how comets moved. He also predicted when some comets which had already been seen would return. For example, Halley’s Comet made its closest approach to Earth for 76 years as predicted in 1986.

Why are comets associated with disaster? It is true that a comet appeared before the Norman conquest of Britain in 1066, and that two more comets were seen before the Great Fire of London in 1666 and the Great Plague in the previous year, but in world terms these cannot be regarded as major events. Perhaps it is the result of people’s belief that what happens in their own country is of world importance that has led to this idea that comets predict disaster. On the other hand, it has been suggested that the Star of Bethlehem that told of the birth of Christ was in fact a comet. It does seem unlikely, however that a body of ice and gas moving around the sky in a quite regular orbit can have anything to do with the events here on Earth. This particularly true of comets because they have such a low density. Although they may have a diameter of as much as 128000 Kilometers they do not have enough gravitational pull to affect the bodies they pass. In fact, their own orbits may be completely changed.

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Inventions, science, useful topics for students.