MARS 



3662 



MARSEILLAISE 



Motions of Mars. Mars rotates on its own 

 axis in 24 hours, 37 minutes, 22 seconds; it 

 requires one year, ten and a half months (687 

 days), as we count time, to complete its jour- 

 ney round the sun. The seasons are similar to 



MARS 



Orbit of Mars and of the other three "inner 

 planets" (between Mars and the sun). 



our own, but are twice as long. The synodic 

 period, that is, the time taken in traveling from 

 conjunction to conjunction, of Mars, is the 

 longest in the planetary system, being 780 days, 

 during 710 of which the planet progresses 

 towards the east, and during the other 70 it 

 retrogrades. 



Comparative Size of Mars. The diameter of 

 Mars is 4,200 miles, about one-half that of the 

 earth. Its surface is about two-sevenths, its 

 volume one-seventh, of that of the earth. Its 

 mass is less than one-ninth that of the earth, 

 and its gravity is about one-third of the gravity 

 of the earth's surface; a man weighing 150 

 pounds on earth would weigh only about 50 

 pounds in Mars. The atmosphere of Mars is 

 probably much less dense than that of the 

 earth, but there are indications that an atmos- 

 phere exists. The disk of Mars is brightest at 

 the edges, or limb. It has been estimated that 

 the albedo, or light-reflecting power of its sur- 

 face, is double that of Mercury, but only half 

 that of Jupiter. 



Satellites of Mars. In 1877 two satellites 

 were discovered by Professor Hall of the Naval 

 Observatory, Washington, D. C. They are not 

 visible to any except the most powerful tele- 

 scopes, for they are among the smallest of 

 known heavenly bodies. The outer one, far- 

 thest from the planet and called Deimos, is 



14,600 miles distant from the center of the 

 planet and completes its revolution in 30 hours, 

 18 minutes. The inner one, Phobos, is only 

 5,800 miles distant, its period being 7 hours, 39 

 minutes. Measurement of the diameter of such 

 small and distant objects is difficult, but Pro- 

 fessor Pickering estimated the diamete^ of 

 Deimos at 7 miles, and of Phobus at 5 or 6 

 miles. 



Canals of Mars. In 1877 the Italian astrono- 

 mer, Schiaparelli, discovered features on the 

 surface of Mars which have given rise to almost 

 endless discussion. Five straight lines, ditches, 

 or canals, as they are now called, cross the 

 ruddy surface of the planet in various direc- 

 tions. So like canals do they seem that some 

 astronomers have maintained that they are 

 artificial, and that they are probably used as 

 irrigation ditches. It is also noticed that these 

 lines do not change their position, though some- 

 times they appear to be double. 



Temperature of the Planet. The surface of 

 Mars appears to be marked with indistinct gray 

 patches, which were at one time assumed to be 

 water; however, as the temperature on Mars is 

 considerably lower than at the summits of our 

 highest mountains below zero, in fact water 

 could not exist. This has led astronomers to 

 conclude that what appear to be polar ice caps, 

 white patches at both poles which increase or 

 dwindle according to the seasons, cannot be ice, 

 but are formed of condensed gases. 



While the differences between Mars and the 

 earth are less than those between any other 

 two planets, it is considered by many scientists 

 that if Mars is inhabited it must be by some 

 beings quite different from the people of earth, 

 but the weight of evidence is against the theory. 

 Others, however, argue that there are "other 

 worlds than ours," and that Mars is one of 

 them. Neither statement can be definitely 

 proved, and Mars will probably continue 

 through the ages a matter of speculation and 

 interest. F.ST.A. 



Consult Housden's The Riddle of Mars, the 

 Planet; Lowell's Mars as the Abode of Life. 



Related Subjects. The reader is referred to 

 the following articles in these volumes : 

 Astronomy Planet 



Conjugation Star 



Mars (war god) 



MARSEILLAISE, mahr sel ayz' , in French, 

 mahrsehyaiz' , THE, the national hymn of 

 France, written by a young officer named Ron- 

 get de Lisle, who composed both the words and 

 the music in a single night during the French 



