470 The Planet Mars. 



126,620,000 miles; his eccentricity, or C'S, is 13/025,000 

 miles. The rising node of the Martial orbit, is in longitude 

 48° 27', measured from S V in the direction of the planet's 

 motion. Mars reaches his greatest distance from the ecliptic 

 plane, near M" (Fig. 2), when his distance from that plane is 

 no less than 4,850,000 miles. 



The point at which the two orbits approach nearest lies 

 nearly in direction O'S, but somewhat precedes that direction, 

 owing to the eccentricity of the earth's orbit. Here the orbits 

 are separated only by 34,140,000 miles, whereas, in direction 

 S C, they are separated by no less than 61,860,000 miles. 

 Hence the planet Mars appears much larger when he is in 

 opposition near perihelion, than w r hen he is in opposition near 

 aphelion. He is also more brilliantly illuminated when in the 

 former position. Hence, when in opposition near perihelion, 

 he shines with a brilliancy comparable to that of Jupiter and 

 Yenus ; and his appearance at such a time has caused alarm to 

 the uneducated. In August, 1719, for instance, when he was 

 only 2^° from perihelion, at the time of opposition, he created 

 the same sort of panic that brilliant comets are apt to produce. 

 His ruddy aspect, which gained for him among the Greeks the 

 epithet 6 irvpoets, tended to increase this effect. 



Since Mars, when he comes to opposition near perihelion, is 

 south of the equinoctial, he attains but a moderate altitude on the 

 meridian, and on this account he is less favourably seen. He is in 

 fact thrown much further south at this time than he would be if 

 he travelled in the plane of the ecliptic. For, although the plane 

 in which he moves is inclined at an angle of only 1° 51' 5" to 

 the plane of the ecliptic, yet, seen from the earth in opposition, 

 when nearly at his greatest distance south of the ecliptic (which 

 happens if he is in opposition near perihelion), he is thrown 

 nearly 7-1° south of the ecliptic. This will be clearly under- 

 stood if we refer to Fig. 2 to exhibit the corresponding projec- 

 tion of Mars north of the ecliptic ; for it will be very evident 

 that Mars, being raised above the plane of the paper at 

 M or M", would appear much more elevated above that plane 

 to an eye placed at or near the centre of E or E", than he 

 would to an eye placed at S. The greatest possible meridian 

 altitude of Mars in our latitude is about 66°, his least scarcely 

 exceeds 10°. Those who are in the habit of using the teles- 

 cope will know very well what this means, and will readily 

 understand that perihelion oppositions of Mars lose much of 

 their superiority, through the comparatively low altitude of the 

 planet on the meridian. Hence far better views of Mars were 

 obtained in 1862 and 1864 than in 1860, though ho was 

 farther off slightly in 1862, and very considerably in 1864, 

 than he had been in 1860. The approaching opposition is 



