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Unit IV

THE EARTH

Reading Material Text a

Task

  1. Before reading the passage discuss these points with a partner.

  • What is the Earth?

  • Is the earth a perfect sphere?

b) Now read the text, translate it and get ready to do the exercises after the text.

This Earth of Ours

Earth is a minute fragment of a universe that is believed to have come into existence1 as a result of a cataclysmic explosion of a single mass of highly concentrated matter some ten billion years ago. Out of this explosion evolved the galaxies, such as our Milky Way, that are made up of the many billions of stars that are known to exist in the heavens.

All of these stars, of which Sun is one, have been rushing farther and farther out into space at an extremely rapid rate ever since. But this rate is now believed to be slowing down2. If so, eventually this expanding movement may come to a halt and its direction may then be reversed. In that event all the separate units of the universe might be pulled back together with a resulting new explosion that would repeat the sequence.

Where Earth had its origin and how it came to be have long been subjects of much speculation among mathematicians and astronomers, geologists and biologists, physicists and chemists, and philosophers and theologians. Some of the more modern concepts of highly capable scientists especially concerned with this subject appear sufficiently conclusive to make it possible to accept them as working hypotheses. But they still leave many points to be more fully explained.

Earth, located some 93 million miles out in space from Sun and revolving around it once every 365 days at a speed of about twenty-two miles a second, is believed to be3 an offshoot from Sun. It came into existence largely as a gaseous mass that began to solidify into its present form some four and one-half billion years ago. It is the third of a series of eight planetary satellites of Sun, of which Mercury and Venus are nearer to Sun, and Mars, Jupiter, Saturn, Uranus and Neptune are increasingly farther away from it.

Our solar system is not unique, and neither is Earth. Many millions of such systems are believed to exist4 in the universe. The number of stars, among the largest of which our sun is a mere midget, has been estimate at 1020 , which means 10 multiplied by itself 20 times. And of these millions of millions of millions of stars, some 108 have been estimated to have5 planetary systems similar to the one of which Earth is a part. From this, one may speculate that there are millions of planets that are so located with reference to the stars round which they revolve as to have conditions that are favorable for life. The living forms on these Earthlike planets may be very different from those with which we are familiar. Conceivably, the highest forms of life on some of these plants may be superior to man.

The history of Earth is recorded on part in the rocks that are exposed to view and that have been reached by quarrying and boring. For convenience, this history is divided into five eras, of which the most recent, the Cenozoic era, covers the last 60n million years, since the folding that formed the Rocky Mountains. The next earlier Mesozoic era, extending back 130 million years farther, began with the folding that formed the Appalachian Mountains. Prior to that were the Paleozoic era of 360 million years following an extended period of widespread overflows of molten lava, the Proterozoic era of 900 million years after the Laurentian revolution, and the Archeozoic era that began in obscurity. These five eras total 2,000 million years, leaving 2,500 million more years to get us back to the beginning of time on Earth.

During the pre-Archeozoic era, Earth was a molten mass, the surface of which was cooling down to form a solid crust of rock. The moist vapor that originally surrounded Earth gradually condensed to form water. This existed mostly as such, but some of it joined to the minerals that formed as the molten rock cooled, and now exists in combined solid form. But the interior of Earth has remained hot down to the present time, the temperature of its central core being estimated to be6, at least 1, 500º C.

Notes:

  1. is believed to have come into existence – полагают, что … появилась

  2. is believed to be slowing down – полагают, что …замедляется

  3. is believed to be – полагают, что … является

  4. are believed to exist – полагают, что …существует

  5. have been estimated to have … – установлено, что …имеют

  6. …, the temperature being estimated to be … – считается, что температура составляет

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