Tour of the Univers and the rotation of the earth|virtual tour of the universe| virtual tour of the galaxy| virtual tour of the planets| virtual tours of the planets for kids
TOUR OF THE UNIVERSE and rotation of the Earth, Let us take you on a tour of the universe. Friends, for a tour of the entire universe, you have to read this article of ours till the end today during most of the nights in Pakistan, the sky is clear and is studded with stars, like pearls fixed in an emerald bowl. We are accustomed to judging the appearance of a thing by the look it presents to our eyes.
But in many a case, our eyes are apt to deceive us. We see the sun rising from the sky, but as a matter of fact, we know that it is not the sun but the earth that is in motion.
Take another example while sitting in a moving train we see that the trees are moving but we know that in reality, the trees are not moving at all. Similarly, when we are standing in the middle of a railway track, it seems that the lines are joining together in the long distance.
But we know that this is all an illusion because the distance between the railway lines is absolutely constant. Now we can ask the question is the sky really like an inverted bowl and is its blue colour like the blue colour of a cup we observe that the colour of the sky is not always blue.
If there is a dust storm, it looks grey. Similarly, if we go 10 or 12 miles up in the air in an aeroplane or in a balloon, it looks brown and if we go up some 20 miles or so, it disappears altogether and we see nothing but darkness all around us.
This clearly shows that the colour of the sky changes in accordance with the conditions that are imposed upon it. All such experiments show that we observe the sky and its colour only on account of the scattering of light which is caused by dust, smoke and air particles in the atmosphere.
We can also cite the example of a rainbow. When we see it, we are sure that it is not real and substantial because it disappears after some time. In.• fact the rainbow is also an optical phenomenon, and we see its colours because, even here, light is dispersed.
Light consists are seven colours violet, indigo, blue, green, yellow, orange, and red. When it passes through prism sunlight is broken up into its component colours, and it is this colour effect that gives us the rainbow. We can also give the example of an image in a looking-glass.
When we see our face in it, we are sure that behind it there is no second face of ours. It is only a light phenomenon or in the language of science an optical phenomenon.
If we go up a thousand miles or so, we shall be invaded by small as well as big balls of stone.
These are called meteors and they move in curved paths due to the attraction of the earth and sun. The earth attracts all bodies, big or small, towards it. When a stone, an apple, or a leaf falls, it moves towards the earth and this obviously shows that the earth attracts all bodies towards it.
Of course, a balloon rises in the air because it is filled with some gas that is lighter than the air. If it is emptied of light gas the same balloon falls to the earth.
Some Of these balls are outside the earth's atmosphere. This atmosphere of the earth extends above our heads up to a distance of a few hundred miles.
When these balls are thousands •of miles away, they move towards the earth at a very, very high speed, much faster than even a bullet. When they reach the atmospheric air, a lot of friction develops and this friction.
produces heat, just as it does when we rub our hands together. In the case of a ball, this frictional heat is so intense that it burns up, and because it moves very fast, producing a bright line in the sky, it is called a shooting star.
Sometimes the ball is very big, weighing several hundred maunds. In such cases, due to intense heat produced by friction, the ball breaks up just like a big firework and we get a fireball.
Now, suppose that we are moving in a rocket bound for the moon. After a flight of a few thousand miles, we shall find the rocket outside
the range of attraction of the earth. Then the rocket will need no fuel and will move of itself towards the moon because she is the nearest heavenly body to the earth.
We know that our earth moves around the sun. There are many Other bodies also, which move around the sun. These are called planets. Mars, Venus, Saturn, Jupiter etc are all planets.
A moon is a body that moves around a planet. There is one moon for the earth. But there are two moons for Mars and 12 moons for Jupiter. Our moon is at a distance of 239,000 miles from the earth. Its diameter is 2,160 miles.
It is not bright itself but when the light 'of the sun falls on its surface, it reflects that light and when it strikes our eyes we see it bright. The black spots on the moon seen by the naked eye are not due to a woman spinning a charkha. The teal structure of the moon is visible in a telescope.
The telescope is a wonderful instrument in which we see heavenly bodies very very big in size. A telescope may be small or big. Some of the big telescopes are 30 or 40 yards long.
When we see the moon in the telescope, we see craters and mountains on it. Some of the craters are more than a hundred miles long. There is no water or air on the moon and so in our journey to the moon, we shall have to take oxygen breathing apparatus along with us.
The temperature Of the moon changes sometimes it is as hot as boiling water and sometimes it is more than a hundred degrees below the ice temperature. A living quarter on the moon, therefore, will not be comfortable. Leaving the moon in our interplanetary travel, we shall reach Mars which is at a distance of miles from the earth.
The diameter of Mars is 4,200 miles. seen in the tele attributed to the presence of vegetation, but the green' colour can also be explained in other ways. From scientific observations, it appears that their moisture and some clouds as well are on Mars. But if at all, water is present on Mars, it is present in a very small quantity. It would only fill an ordinary lake. There seems to be snow on the Martian mountains. It is probably not of water but of solid carbon dioxide.
The temperature on Marsxanges from 500 F to—940 F. There are also observed, what appear to be canals, on Mars when seen in the telescope. About 430/0 of the
sunlight reaches Mars as compared with that which reaches the earth and hence some vegetation is possible there. But it is not definite whether the canals contain water, because they may be only optical illusions.
On the whole, life on Mars seems possible. Mercury is a planet that is also our neighbour. But its view in the telescope is very desolate and dark, and there appears no sign of air, water or vegetation on it.
Venus comes next and its distance from us is 27,000,000 miles. Shining in the twilight sky, it makes a spectacular object to show our friends through the telescope. There seems to be a thick atmosphere around it but the quantity of oxygen is so little that there is little prospect of life on Venus.
Often we see only a line of its disc and the resemblance between it and the new moon is so striking that often people mistake the former for the latter. Now we come to big planets which we may call giant planets.
These will be Jupiter, Saturn, Uranus, and Neptune. Inside these planets, the matter is at a pressure of hundreds of tons per square inch and such pressure would even make a gas solid!
In fact, we can't describe the state of matter inside a giant planet to be anything similar to that found on earth. On some of these planets, we have an atmosphere not of air but of hydrogen.
Within the giant planet Jupiter the pressure may be as high as 800,000 times that of our atmosphere. At this pressure, hydrogen will be in a solid-state.
In a telescope, the planets appear like discs of finite diameter, but if we look at the stars we find that, even in the biggest telescope, a star will appear just as a point. The distance of stars is far too big to be described in miles. It may well be described in terms of the speed of light, which is 1,86,000 miles per second.
The nearest star, Proxima Centauri, is so far off that its light takes over 4 years to reach the earth. In the case Of some of the stars, light takes millions of years to reach the earth! The stars have different colours, red, blue, yellow, etc.,
According to their temperature which is, sometimes, millions of degrees. At this temperature, the atom is Now we come to big planets which we may call giant planets. These are Jupiter, Saturn, Uranus, and Neptune.
Inside these planets, the matter is at a pressure of hundreds of tons per square inch and such pressure would even make a gas solid! In fact, we can't describe the state of matter inside a giant planet to be anything similar to that found on earth. On some of these planets, we have an atmosphere, not of air but of hydrogen. Within the giant planet Jupiter the pressure may be as high as 800,000 times that of our atmosphere. At this pressure, hydrogen will be in a solid-state.
In a telescope, the planets appear like discs of finite diameter, but if we look at the stars we find that, even in the biggest telescope, a star will appear just as a point. The distance of stars
is far too big to be described in miles. It may well be described in terms of the speed of light, which is 1,86,000 miles per second. The nearest star, Proxima Centauri, is so far off that its light takes over 4 years to reach the earth.
In the case Of some of the stars, light takes millions of years to reach the earth! The stars have different colours, red, blue, yellow, etc., according to their temperature which is, sometimes, millions of degrees.
At this temperature, the atom is smashed and it splits up into pieces, thus making the stars large store-houses of atomic energy. about to science brightest star in the sky is Sirius. It is the first to appear after sunset.
Some of the stars are fixed in position. They tell us about the north-south direction and the pole-star belongs to this category. Again some stars are grouped into clusters to which different names have been given, e.g., the Great Bear, the Scorpion, the Great Dog, etc.
The Milkyway is a cluster of millions of stars huddled together. If we look at it in a big telescope, we observe a long river of minute specks of light. The star clusters appear and disappear at definite times of the night.
This gives people an idea of time. Now let us say something about the sun also. There are, however, many suns in the Universe and our sun whose diameter is a million miles is at a distance of 93,000,000 miles from use The material in it, however, is of diverse texture.
On its surface, there are very hot gases, giving fire blasts that are thousands of miles high. In a solar eclipse, these high flames of fire are clearly seen with the help of a telescope. The temperature on the surface of the sun IS about 6,000 degrees, but the temperatures inside the sun are millions of degrees.
The light and the heat of the sun have been coming out for millions of years. What is the source of this heat and light?
The answer is the Hydrogen bomb. Inside the sun millions of Hydrogen bombs are bursting every day and the energy of all these hydrogen bombs gives us the heat and the light of the sun.
Inside the sun all the matter has been smashed into atoms and the atoms have been split into parts.
This is due to the intense heat which exists inside the sun. The pressure inside the sun is so terrific, that it amounts to millions of tons per square; Inch. Thus inside the sun and some of the stars a thimble-full of matter will weigh several tons.
The nebulae are hazy, bright patches visible in the heavens. They are so far away that even the biggest telescope cannot give their complete details. They are so big that in some of them universes like our own containing suns etc., are being created. Equally amazing are other facts of the science of astronomy.
Our solar system is moving at a breakneck speed and it is one of the wonders of God's sublime nature that there is no collision of any of the members of our Universe. In this atomic age, a trip to Mars and the moon may become possible.
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