Category Archives: HOW?
34.DO HURRICANES MOVE IN DEFINITE DIRECTIONS?
A storm or a hurricane seems such a wild, uncontrolled thing that it’s hard to believe it is following a definite path. Yet, as we know, when the hurricane season starts, the hurricanes are given names and their courses are often predicted very accurately!
In most parts of the world, most storms do move in definite directions. In the United States, for example, most big storms are vast circular whirls of air that rotate counterclockwise about a central point of low atmospheric pressure. The reason they rotate counterclockwise in the United States is that, as winds flow in toward the center of low pressure, the earth’s rotation deflects them toward the right (in the Northern Hemisphere).
28.WERE THE CONTINENTS EVER JOINED TOGETHER?
Take a look at a map of the world. Now look at the two continents of South America and Africa. Do you notice how South America sticks out to the right where Brazil is, and how Africa is indented on the left side? Doesn t it seem as if you could fit them together like a puzzle and make them one continent?
Well, 50 years ago a German scientist named Alfred Wegener was doing just that. He wrote: “He who examines the opposite coasts of the South Atlantic Ocean must be somewhat surprised by the similarity of the shapes of the coastlines of Brazil and Africa. Every projection on the Brazilian side corresponds to a similarly shaped indentation on the African side.”
Wegener also learned that naturalists had been studying the prehistoric plant and animal life of South America and Africa and had found many similarities. This convinced him that these two continents were once attached and had drifted apart.
He formulated a theory which he called the theory of the displacement of continents. According to this theory, the land masses of the earth were once all joined together in one continuous continent. There were rivers, lakes, and inland seas. Then fpr some unknown reason, this land mass began to break up. South America split off from Africa and drifted away. North America split off from Western Europe and floated to the west. All of the continents as we now know them were thus formed.
Did this actually happen as Wegener says it did? We don’t know. It’s only a theory. But as you can see from the map, there is some evidence to support it. And the study of prehistoric plant and animal life makes it seem possible, too. Besides, the earth’s crust is still shifting today. So perhaps Wegener was right!
27.HOW WAS THE PLANET PLUTO DISCOVERED?
If you think it’s hard to find a needle in a haystack, just consider the problem of “finding” the planet Pluto. It is the outermost planet of our solar system, almost forty times as far from the sun as the earth! It is so faint that a good-sized telescope is necessary to even see it. Yet, somehow it was discovered. How was it done?
There are two sets of laws that help man obtain knowledge of the sizes of planets and their distances. Kepler’s laws of planetary motion made it clear that the orbits of the planets around the sun were not quite circles.
