At the dawn of the space age, it seemed that we knew more about the Red Planet than they did in earlier times. But we still did not have the "full picture." Here is an account from an encyclopedia from 1951. How did our view of Mars change between this account and the earlier ones? What did we really learn in the eighty years between this and the first account from 1870? Test your knowledge by visiting the Old Mars Quiz Page, linked at the end of this section.
The Book of Knowledge - Vol. 9
Excerpt from "The Terrestrial Planets"
By Marian Lockwood
Copyright 1951 by the Grolier Society, Inc.
Ruddy Mars, the Earth's Other Near Neighbor
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| An imaginary picture of "life on Mars." Any life on that planet would be very different from ours. |
The earth is flanked on one side by her beautiful and brilliant neighbor Venus, and on the other by the ruddy and warlike Mars. Of all the planets in our solar system, Mars is to the average person the most interesting. It has long been the "best seller" among planets because decades ago some astronomers came to the conclusion that there might conceivably be life there. That is a fascinating thought; but let us see first what Mars looks like and what its physical characteristics are, before we examine this question of life.
Mars in itself is an interesting planet, even omitting the possibility of life there. We can observe it more easily than any other planet because of its nearness to the earth (only Venus among the planets comes closer) and because of its very thin atmosphere which produces no heavy clouds to hide the surface from our curious gaze.
It was undoubtedly because of Mars's red color that the ancient astronomers gave it the name of the god of war, for red is a color associated with battles and bloodshed. This red color is caused by the oxidation of iron on the surface of the planet--in other words, Mars has rusted. Some day in the far future, it is probable that the surface of the earth will for this same reason take on a similar reddish tint.
Mars is slightly more than half the diameter of the earth, and is so much less massive than our planet that your weight there would be much less than it is on the earth. The day is just 37 minutes and 58 seconds longer than our day on the earth. Mars has two moons revolving around it very rapidly. Phobos, the nearer moon, with a diameter of about 15 miles, travels around Mars in 7 hours and 39 minutes. Deimos, the outer and smaller of the two, takes 30 hours and 18 minutes to complete its circuit. (Neither Venus nor Mercury has any moons.) Phobos travels so much more rapidly than Mars itself rotates that an observer on Mars would see this tiny moon rise and set several times a day; and Phobos would rise in the west and set in the east because of this rapid revolution.
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Right - During summer in the northern hemisphere on Mars, the ice around her north pole melts. Left - In early spring, the icecap is larger. Of course, we can only guess that these white caps are ice. |
One of the most interesting features of Mars is the presence of the two polar caps, white patches which occur at the planet's north and south poles. These polar caps vary in size with the changes of the Martian seasons which are approximately twice as long as ours. In winter the polar caps are extensive, sometimes reaching more than halfway to the equator. (Of course the same thing is often true on the earth in the winter time.) Then, when the Martian spring and summer come, these polar caps begin to shrink in size until sometimes they almost entirely disappear. Naturally, astronomers have wondered if the caps are not composed of snow and ice like our own terrestrial polar caps. Although we are not sure, it seems most probable that this is true.
Percival Lowell's Ideas about Life on Mars
Toward the end of the last century an American astronomer, Percival Lowell, began a study of Mars and its peculiar surface markings which was to occupy him for the rest of his lifetime and to make him one of the greatest students of Mars. Lowell believed that the peculiar dark lines on the surface were actually artificial waterways or canals, built by intelligent beings to carry water from the melting polar caps to the more arid and desert-like sections of the planet. Very few astronomers would agree today with Lowell's belief. At such a great distance (at its closest approach Mars is about 35,000,000 miles from the earth) it is impossible to determine whether the dark lines are straight or whether the appearance of straightness is merely an illusion caused by distance.
The presence of living creatures on Mars seems unlikely because there is an infinitesimally small amount of oxygen in the atmosphere, something like 1/10th of one percent (1/1000) as much per unit of volume as in the air of the earth. The Martian atmosphere is probably only about 60 miles in depth, as compared to the 500- or 600- mile depth of the earth's envelope of air.
We can not say definitely that there can be no animal life on Mars because, as some authorities suggest, Mars probably once had a much heavier atmosphere than it has today. If beings existed there at that time, they might have gradually adapted themselves physically to the slow loss of oxygen from the atmosphere, or even have built themselves cities with artificial atmospheres under cover. But this is in the realm of wildest speculation, and nothing whatever is known definitely about life on Mars.
While this great doubt exists as to the presence of animal life on Mars, many astronomers believe that plants may grow there. Certain seasonal changes in color, green areas appearing in the spring and summer, seem to indicate that vegetation is coming to life at those times on Mars, as it does on the earth in the spring. If plants do exist there, we might expect that they would be of the same general type as terrestrial plants found in deserts and at high altitudes.
Mars as a whole is a much colder planet than the earth. Temperatures in some of the green areas have been found to be as high as 86 degrees F. at noon, while in the early Martian evening the temperature falls to about 10 degrees F. At midnight it must be very cold indeed, far below zero.
While we have given to various dark areas on the red planet the names of lakes, bays, channels and seas, there are in reality probably no large bodies of water there. Any large area of water would reflect sunlight so conspicuously that it would be observable with our telescopes, and no such reflection has ever been seen.
It is interesting, in comparing our two closest neighbors among the planets, to note that some astronomers think Venus is in an earlier stage of development than the earth, perhaps as the earth was millions of years ago. Mars, on the other hand, shows all the evidences of a slowly dying planet, presenting perhaps a picture of the earth as it may be ages from now.
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