Tell me why

                                 WHAT IS THE MILKY WAY? There is probably nothing more mysterious and wonderful-looking in the sky than the Milky Way, stretching like a band of jewels from one end of the sky to the other. In ancient times, when people gazed at this spectacle, they were filled with the wonder and beauty of it just as you are. But since they didn't really know what it was, they made up all sorts of strange and beautiful explanations of the Milky Way. For example, in early Christian times, people thought it was a pathway for the angels, so they could go up to heaven on it. Or they imagined it was an opening in the heavens, so that we here on earth could have a glimpse of the glory that existed beyond. Knowing the facts about the Milky Way, as we do today, doesn't remove any of the wonder of it. The facts are just as amazing as any "made-up" idea! Our galaxy is shaped roughly...

                                     WHAT IS A CONSTELLATION? Have you ever looked at the stars and traced out squares, letters, and other familiar figures? In nearly all parts of the world, people of long ago did this and gave names to the group of stars they observed. Such a group is called "a constellation," from the Latin terms meaning "star" (stella) and "together." The names of the constellations in use today have come down to us from the times of the Romans and from the even more ancient Greeks. What the Greeks knew about the stars came partly from the Babylonians. The Babylonians named some of their star figures after animals and others after kings, queens, and heroes of their myths. Later, the Greeks changed many of these Babylonian names to the names of their own heroes such as Hercules, Orion, and Perseus. The Romans made further changes. The same ancient names are st...

                                                    WHY ARE ECLIPSES SO RARE? When the moon in its journey around the earth passes directly between the earth and the sun, it casts its shadow on the surface of the earth, and an eclipse of the sun takes place. An eclipse of the sun occurs only when the moon is new, for then the moon is on that side of the earth facing toward the sun. Then why isn't there an eclipse of the sun every time there's a new moon? The reason is that the path of the moon around the earth does not lie directly in line with the orbit of the earth about the sun. In its 29-day trip around the earth, the moon passes sometimes above and sometimes below the path of the earth. An eclipse of the sun can be total, annular, or partial. If the moon hides the sun completely, the eclipse is total. But the moon is not always t...

                                 WHAT IS THE EARTH MADE OF? Man is now preparing to explore the moon and other planets-and he till doesn't know exactly what his own earth is made of! A sort of rough answer to this question would be: The earth is a big all, or sphere, made mostly of rock. Inside the earth the rock is melted, but me outside cover is hard rock. Less than one-third of the earth's surface is and and more than two-thirds are water. Now let's consider this in a little more detail. The outside of the earth s a crust of rock about 10 to 30 miles thick. This crust is sometimes called "the lithosphere." The high parts of this crust are the continents, and the low parts of it hold the waters of the oceans and the great inland seas and lakes. All the water on the surface, including the oceans, lakes, rivers, and all the smaller streams, is called "the hydrosphere." Men have ...

                                        WHY DO SUNSETS LOOK RED? A beautiful red sunset, the colors warm and glowing, is one of the love- liest sights we can imagine. And sometimes, when we look at it we might say, "See how red the sun is!" But, of course, we know that the sun itself hasn't become red or changed in any way. It merely looks that way to us at that particular time of day. In fact, at that very moment people are looking at that same sun thousands of miles to the west and it doesn't look red to them at all. What produces the colors of a sunset is the distance that the sunlight must travel through our atmosphere. The lower it is, the more of our earth's atmosphere does that light travel through.  But first, let's remind ourselves that sunlight is a mixture of light of all colors. Normally, this mixture of light appears as white to our eyes. But the atmo...

                                               WHAT KEEPS THE SUN SHINING? It may be hard for you to believe, but when you look at the stars that shine at night and the sun that shines by day, you are looking at the same kinds of objects! The sun is really a star. In fact, it's the nearest star to the earth. Life as we know it depends on the sun. Without the sun's heat, life could not have started on earth. Without sunlight, there would be no green plants, no ani- mals, no human beings. The sun is 93,000,000 miles from the earth. The volume, or bulk, of the sun is about 1,300,000 times that of the earth! Yet an interesting thing about the sun is that it is not a solid body like the earth. Here is how we know this: The temperature on the surface of the sun is about 6,000 degrees centigrade. This is hot enough to change any metal or rock into a gas, s...

                           WHY IS THE SOLAR SYSTEM THE WAY IT IS? As far as we know, there is no reason why the solar system is arranged exactly as it is. It might have been arranged differently, just as there are other solar systems in the universe arranged differently. This has to do with the way it originated. But man has discovered certain laws of nature that seem to keep the solar system in its present pattern. Earth, like the other planets, follows its path, or orbit, around the sun. The period of time that the earth takes to go around the sun is called a year. The other planets have orbits larger or smaller than the earth's. How this solar system came to be and how the planets came to have the size, location, and orbits they have, astronomers cannot fully explain. But they have two main types of theories. One type of theory suggests that the formation of the planets was a part of the gradual chan...