We have learned much about the Red Planet over the last fifty years. Here is an account from an astronomy textbook written in 1870, over 130 years ago. Everything written below was based upon Earth-based observations through telescopes; indeed, all of these accounts have that in common. What aspects of Mars did they get correct? What did they get wrong? What have we discovered through the use of remote observation of Mars with robot spacecraft? Test your knowledge by visiting the Old Mars Quiz Page, linked at the end of this section.
A Short Course in Astronomy
By Henry Kiddle, A.M.
Superintendent of Schools, New York.
Ivison, Blakeman, Taylor & Co. 1870
Mars
121. Mars. The fourth planet from the sun, is remarkable for its small size and the red color with which it shines among the stars. It is consequently very easily distinguished from the other heavenly bodies, and doubtless received its name on account of this red appearance, Mars being the god of war. Its sign is a shield and spear.
122. Orbit. The eccentricity of its orbit is nearly 5 1/2 times as great as that of the earth's, it being about 26 millions of miles nearer to the sun in perihelion than in aphelion. Its inclination of orbit is about a degree and a half.
Owing to the great eccentricity of the orbit of Mars, it sometimes, when in opposition, approaches very near to the earth; for if it is in perihelion while the earth is in aphelion, the distance is 126,300,000 - 93,000,000 = 33,300,000.
123. Seasons. Since the inclination of its axis is nearly the same as that of the earth, the variety of seasons must be the same; but they must be nearly twice as long, because it takes Mars nearly two years to revolve around the sun. Owing to the great eccentricity of its orbit, summer in the northern hemisphere must be only four-fifths as long as in the southern; and at each of the poles there must be, alternately, constant day and constant night, each lasting nearly one of our years.
124. Telescopic Appearance. The telescopic appearances of this planet are very interesting, exhibiting what seem to be the outlines of continents and seas, the former appearing of a ruddy or orange color, and the latter of a dusky greenish or bluish tint. Brilliant white spots are also seen alternately at the poles, evidently produced by accumulations of ice and snow during the long winters, particularly as they are seen to disappear as summer advances. Evidences are also presented of an atmosphere, probably equal in density to that of the earth.
No entirely satisfactory cause has been assigned for the ruddy color of this planet. It is thought by Sir John Herschel to be due to "an ochrey tinge in the general soil, like what the red sandstone districts on the earth may possibly offer to the inhabitants of Mars, only more decided." Viewed through a telescope, the redness of its hue is very considerably diminished.
Northern and Southern Hemispheres of Mars - Mädler |
The picture above does not represent any actual telescopic views of the planet, since we are never so situated as to be able to see the whole of either the northern or southern hemisphere at any one time. It exhibits a combination of a large number of telescopic appearances, the various dusky spots being placed together so as to show the forms of the different bodies of water and their relation to the continents; the latter being indicated by the white spaces. These, through the telescope, appear of a ruddy color, and give this general tint to the planet. On the earth, the continents are islands; being encompassed by the water; on Mars, it will be perceived, the bodies of water are lakes or seas, being entirely encompassed by land.
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