Английский для бакалавров. Зарубина Л.П - 202 стр.

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Text 5. OUR SOLAR FAMILY
Our solar family consists of the sun, nine known planets and their satellites, as-
teroids, comets and meteors.
The most important body in this great family is the sun. There are few kinds of
energy on the earth that are not the gift of the sun.
The sun's mass is 750 times that of all the planets, put together. Like all the other
bodies in the iniverse, it is composed of the same sort of materials we find on the
earth. Of all the elements or building blocks of nature which we have discovered,
some 68 have been found on the sun, and none have been found in the sun which are
not now known on earth.
Our sun has a surface temperature of about 6,000°C. A star as hot as the sun
must radiate an enormous amount of heat.
Every square metre of the sun's surface radiates energy equal to 84,000 horse
power. Yet, the total amount the earth receives is only a very small fraction of it.
Here is a possible source of energy for the future. The age of the earth is about two
billions of years. The sun must have been in existence long before the earth was
formed. During all that time the sun has been radiating heat continuously, and still
continues to do so. To produce this great amount of heat would require the hourly
burning over its entire surface of a layer of highgrade anthracite coal sixteen feet
thick. If the heat of the sun were produced by burning coal, it would require an inex-
haustible supply to furnish such intense heat over this great period of time.
THE PLANETS
Planets, the most important bodies of the sun's family, are of greatest interest to
man, not simply because they are nearest to him, but because he lives, works, and en-
joys life on one of them. If somewhere life similar to ours exists, we must look for it
on planets, not on stars, comets, or meteors.
The sun has a family of nine planets moving around it in orbits that are ellipses,
and not circles. Their names in order from the sun are Mercury, Venus, Earth, Mars,
Jupiter, Saturn, Uranus, Neptune, and Pluto.
The ancients recognized that these bodies did not remain fixed, but were con-
stantly shifting their positions on the celestial sphere night after night and month af-
ter month; so they named them planets, which means "wanderers."
Mercury is not only the nearest planet to the sun, but it is, with one possible ex-
ception, the smallest of the planets. It is the swiftest in its movement about the sun,
and its year consists of eighty-eight days. Because of the difficulty of locating it in
the bright twilight, it has been called the "elusive planet. " Venus is the brightest star
in the sky, next to the sun and the moon. When it appears as an evening or morning

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