90 SCENERY OF THE HEAVENS. 



" But most is Mars amisse of all the rest ; 

 And next to him old Saturne." 



If Spenser were alive now, he must admit his words to involve a libel upon a very harm- 

 less body, fit to be commended to the inhabitants of the earth as an example of peace- 

 fulness and order, rather than regarded as a patron of belligerent propensities, delighting 

 in " manslaughter and byrnyngs of houses, and in warres," as an old almanac states. 

 The planet is placed in the system at a mean distance from the sun of 142 millions of 

 miles, which is nearly fifty millions of miles farther than the earth. The space, how- 

 ever, between us and Mars varies prodigiously. Sometimes, when he is in opposition, 

 and has the earth between him and the sun, his distance is not greater than that just 

 stated ; but when he is in conjunction, or beyond the sun, his distance is increased by 

 the whole diameter of the earth's orbit, and amounts to upwards of 240 millions of miles. 

 On this account, the apparent size of the planet varies greatly from a diameter of 18" to 

 4". He thus dwindles from a considerable orb in the heavens to an insignificant speck, 

 presenting a faint hazy appearance when most remote from us, and contending with 

 Jupiter for the palm of splendour under a favourable juncture of circumstances. An era 

 of this kind occurred in the month of August, 1719, when Mars was not only in opposi- 

 tion, but within 2\ of his perihelion, that is, the two events were almost coincident, of 

 being nearest the earth and nearest the sun, and then his appearance was so brilliant as 

 to fill the minds of the vulgar with alarm, being mistaken for a new luminosity in the 

 skies. 



The planet has been closely watched by many accurate observers, and his elements are 

 known with considerable precision. Mars accomplishes his revolution round the sun in 

 686 d 23^ h , the length of his year, extending to nearly two of ours, travelling at the rate 

 of 54 thousand miles an hour. In traversing the zodiac, he appears to move at the rate 

 of about half a degree each day, passing through a whole sign in somewhat less than sixty 

 days. Hence, if we know what constellation Mars has just entered, we may conclude 

 that two months afterwards he will be in the next, and four months afterwards in the 

 next, and six months after the date in the succeeding one. His period of rotation upon 

 his axis is 24 h 39 m 21 s , but a slight difference in excess from the length of the terrestrial 

 day. His true diameter is computed to be 4100 miles, rather more than one-half that of 

 our globe, and his volume is about one-fifth. His form is spheroidal, the diameter at the 

 equator being one-sixteenth more than at the poles. From his period of rotation being 

 so nearly equal to that of the earth, while his diameter is very little more than one-half, 

 it might have been concluded that the inferior velocity of his equatorial regions would 

 have produced a much less bulging out there than at the equator of the earth. But 

 while the equatorial diameter of our globe exceeds the polar by twenty-six miles, that of 

 Mars does so by two hundred and fifty, which gives a greater degree of oblateness to his 

 form, and is probably due to his far inferior density. If the orbital career of the planet 

 were suspended, his mass would plunge to the sun in 121 days 10 hours. To Mars, the 

 solar diameter will appear one-third less than to us, and the solar light and heat be pro- 

 portionably diminished ; but his night-sky will be adorned by our globe and its satellite, 

 a beautiful pair of objects, about a quarter of a degree distant from each other. 



The physical constitution of Mars is in many respects analogous to that of the earth. 

 Indeed, the agreement between them is greater than between any two bodies in the system, 

 as far as our knowledge extends. An atmosphere surrounds the planet. His ruddy 

 complexion, observed in very ancient times, has been attributed to its density, and 

 regarded as a phenomenon similar to the redness of our morning and evening sky near 

 the horizon, which arises from the sun's rays passing through the densest part of our 

 atmosphere, which reflects or absorbs the other colours ; while the red rays are those which 



