Descriptive Astronomy; An Elementary Exposition of the Facts, Principles, and Theories of Astronomical Science (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 edition. Excerpt: ...if he could live there and exert the same energy, could jump 30 feet high. Volcanic activity on the moon would throw matter six times as high as the same activity on the earth. Since matter weighs less on the moon, mountains could be piled six times as high before the rock would crush and break out at their bottoms. Perhaps this partly explains why mountains are so very high and rugged on the moon, as we shall presently see. Atmosphere of the Moon. The moon has little or no atmosphere. This is proved by the fact that its surface always stands out with remarkable distinctness, there never being the slightest evidence of clouds or obscuring vapor. It is also shown by the fact that when the moon passes between us and the sun there is no luminous ring around it as there would be if it had an atmosphere. The difference is conspicuous when the planet Venus passes between us and the sun. This planet has an atmosphere and the illuminated ring of its gaseous envelope is visible when it is in a line with the sun. One might well ask why the moon has no atmosphere. The theory has been suggested that it has been gradually absorbed by the rocks of the surface. This is not very probable because while the rocks may absorb some atmosphere, on the other hand, they also give it forth. As they disintegrate they liberate as a rule large quantities of gas. Also there are irregularities on the surface of the moon which, if interpreted as indicating volcanic activity in past times, means that large volumes of gases have been given forth from its interior. A better explanation, and one which is almost certainly correct, is that the moon has not sufficient gravitative power to hold an atmosphere. As was explained above in connection with the atmosphere of the earth and...