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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How long has man been walking the Earth?

Ever since the philosopher and naturalists, Charles Darwin, and his contemporaries including Wallace, suggested that man had evolved from apes, there has been a continuous, and almost frantic quest for evidence of our ancestors. Of course, where we come from has always been a fascinating question, but it is only comparatively recently that systematic searches have been made for traces of ancient men by such eminent scientists as L.S.B. Leakey and still more recently by his son, Richard. As you might imagine, the idea that man came from monkeys brought with it a great deal of public outcry, and in fact, modern research has shown that man did not descend directly from apes but that the apes and man evolved from a common ancestor.

As you know the first thing that monkeys, apes and man have in common is that they all have backbones, so that they all vertebrates. Many characteristics in man have arisen from living in trees. We share them with other primates, as monkeys, apes and man is known. If you suddenly found that you has to live in a tree, what do you think the most use-full adaptations would be? There would bot be much point in having hoofs like a horse which help the horse to run fast. You would need to be able to hold on to the branches, however, as our hands are well able to do. If you wanted to jump from branch to branch, you would have to be able to judge distances. You would need stereoscopic vision, that is, two eyes positioned at the front of your head, not at the sides as in a fish. You are unable to smell the traces of scent that a dog can, but you do have a much enlarged brain. It is the growth of the brain that has enabled man to leave the comparative safety of the trees and compete with the other ground-dwelling animals that are stronger, have better hearing and sense of smell, can run faster and have warm coats to protect them from the extremes of climate.

As you might expect, because man and apes have developed from a common ancestor, it is not easy to tell when the remains of the primates that have found are of men-like apes or ape-like men. But between ten and fifteen million years ago a creature which has been called a Ramapithe-cus lived in parts of Africa, Asia, and Europe. This may have been the ancestor of man and the other apes, though recent evidence suggests that out ancestor was another creature, the ancestor of the orangutan. However, the groups became increasingly diverse until the first creature that could be called human arrived. This was around four million years ago.

How "Ida" named new fossil help the study about human origins?

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What is the importance of Plants in life’s framework?

It is only when we stop to think that we realize the importance of land plants to us. We eat them in our cereals and vegetables, we make use of them for fibers like cotton, we depend on them for many drugs such as penicillin. But even when we eat meat, we must remember that the animals which produce the meat probably lived on Plants.

Plants are nature’s producers. From sunlight, oxygen, and other foods from the soil, plants manufacture the foods upon which all animals ultimately depend. It is worth noting that it was with the rise of land plants in the Devonian, that land animals also began to evolve.

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What is the largest freshwater fish in the world?

The Arapaima from South America is generally thought to be one of the largest freshwater fishes in the world. The biggest one found is said to have been 15 feet in length with a weight of over 400pounds. Most are between 7 and 8 feet long with a weight of 200 pounds, but even this is a colossal size for a fresh water fish.

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