The Moon

 By Bruce Shawkey

Found this interesting book on the Internet, The How and Why Series, this one talking about the moon

The book was written in 1960, before the moon landing, so much has been learned of the moon since the book was published. But still, observations of the moon are pretty much spot on.

Here is what the book had to say:

Our nearest neighbor in space, the moon, appears to be made of rock, not much different from the rocky part of the earth. Indeed, it must have come from the same source as the earth. Some scientists think it was actually torn from the earth, leaving the basin of the Pacific Ocean.

Since, on the average, it is less than 235,000 miles from the surface of the earth, we can make out some features of the moon's landscape, even without a telescope. With the largest telescopes, the magnified image of the moon is equivalent to what you could see with the unaided eyes at a distance of less than 200 miles. This is near enough to make out objects only a few hundred feet apart. You can go exploring on the moon with almost any telescope that can be firmly supported. Even field asses show some of the major features.

Accounts of what the first men to land on the moon will find are so common that the “geography” of the moon is becoming more familiar than some parts of the earth. We all know that the explorers will find no atmosphere, no air or other gases. We know that the sky will be black, with both sun and stars shining at the same time by day. Men will weigh less, because the gravity of the moon is less than that of the earth. And we know that they will find no plants or animals and no soil. The moon is an utter desert.

Accounts of what the first men to land on the moon will find are so common that the “geography” of the moon is becoming more familiar than some parts of the earth. We all know that the explorers will find no atmosphere, no air or other gases. We know that the sky will be black, with both sun and stars shining at the same time by day. Men will weigh less, because the gravity of the moon is less than that of the earth. Arid we know that they will find no plants or animals and no soil. The moon is an utter desert.

The moon’s physical features have been known for centuries. Galileo was the first to train a telescope on it and see its landscape in detail, but centuries earlier men had named the major features that make up the pattern we see as “the man in the moon.” These most noticeable features are broad dark areas, more or less circular. The earliest observers thought they were seas and gave them fanciful Latin names like the Sea of Serenity (Mare Serenitatis), Sea of Rains (Mare Ibrium) and Bay of Rainbows (Sinus Iridium). These dark blotches cover about half of the moon’s surface. We now know there is no water on the moon. The areas called seas are broad plains, possibly of hardened volcanic lava and probably covered with dust and gravel. Around these plains the landscape of the moon is extremely rugged, with craggy mountains rising above the plains nearly as high as Mount Everest.

These mountains are made up of craters, which make the moon look like a giant’s battlefield. There are two theories about the formation of the craters — one, that they were formed by meteors striking the moon; and, two, that they are extinct volcanoes. It may be that both forces have been at work.

There are also cracks in the surface called rills. These probably opened up as the moon cooled. And there are the mysterious rays. These are white streaks from some of the craters, They run across mountains and plains, in some cases as far as 1,500 miles. They may be dust scattered by whatever explosions produced the craters,

The moon has important effects on the earth. The chief of these are the tides of the oceans. Tides are caused by the pull of the moon and, to a lesser extent, of the sun. The moon pulls the earth out of shape as shown in the illustration. As the earth rotates, these bulges in the oceans move around the earth causing two high tides and two low tides every day at points on the shore. The pull of the moon, along with that of the sun, makes the earth wobble as it spins, which makes no end of complications in the calculations of astronomers.

Since we live on the earth, the study of the planet itself does not come under the science of astronomy. Because of the wealth of information available, its study is divided among a number of other sciences. However, the astronomer is concerned with the motions of the earth in space. These motions are of the greatest practical importance to us. They produce night and day, the seasons, and our calendar. Knowledge of them is necessary for time-keeping and navigation.