SOLAK SYSTEM. 



SOLAK SYSTEM. 





8. This mode of designation has recently been abandoned. It in 

 now iuiul to distinguish the asteroid) merely by a number, enclosed 

 in a circle, indicating their place in the order of duo>\ > ry. 



I'l-inus bat been HjtingiiiAj by the initial letter of Hcrschel's 

 name, with the symbol of a planet attached, y ; Neptune ha* for its 

 (ynibol a trident, "-p. 



We are now to taU< the relative dimension* of the Solar System in a 

 rough manner. Thu, we think, it may be useful to do in such a manner 

 that any two planets may be compared with ono another without com- 

 putation. The planet Ceres is used to represent the group of minor 

 planets. 



And first, as to the relative distances from the Sun, we hare the 

 following table : 



100 

 187 



m 



. .; 



718 

 1344 

 2464 

 4965 

 7740 



54 

 100 

 1S8 

 811 

 ; M 

 7i9 

 1319 



4140 



. 



72 

 100 

 162 

 277 



954 

 1918 



; 



26 

 47 



100 



182 



341 



626 



1259 



1980 



16 



26 



36 



55 



100 



187 



847 



600 



10M 



74 



139 



192 



293 



632 



1000 



1833 



5681 



K76 ' 



41 



76 



106 



160 



290 



645 



1000 



2010 



BUM 



20 



88 



62 



79 



144 



271 



497 



1000 



1560 



14 



24 



84 



62 



95 



176 



323 



649 



1000 



Thu table represents the comparative mean distances of the planets 

 from the Sun. In each column one of the Hfanr is made 100 

 or 1000, and the rest are expressed accordingly. Thus we see by 

 inspection that Uranus is about 124 times as far from the Sun 

 as Mara ; about 19 times as far as the Earth ; about 26 J times as 

 far as Venus; and about 7J times the mean distance of the four 

 small planets. Also, taking the mean distance of the small planets, 

 we see that the distances from the Sun are as the numbers 15, 

 26, 36, 55, 100, 187, 347, 690; and if we take the first away from 

 all the rest, we have 11, 21, 40,85,172, 332, 675, 1071, in which 

 it will be observed that each is about double of the preceding, except 

 in the case of the last two numbers. Kepler had observed a pro- 

 gression, without assigning a law, and had also noticed that one term 

 appeared to be missing. Bode assigned the law which has just been 

 noticed, noticing also the apparently missing term. The existence of a 

 planet between Mars and Jupiter was accordingly suspected ; and at 

 last, to the astonishment of astronomers, four little bodied, looking 

 more like fragments of a planet than planets, were discovered at a 

 distance from the Sun so near to that which had been suspected, that 

 their mean distance fills up its place in the series as well as that of any 

 other planet. It was of course immediately suspected (when only two 

 had been discovered) that these were remains of some planet which 

 had been shattered by explosion or other cause ; and the encourage- 

 ment which this idea gave to look for further fragments, was perhaps 

 one of the main causes of the discovery of the remaining two. It has 

 been already stated that the number of bodies constituting the group 

 of minor planets now amounts to sixty-four. This law of Bode, as 

 it has been called from the astronomer who first noticed it, may be thus 

 expressed : if a be the distance of Mercury, and a + b of Venus, then 

 a + 26 is that of the Earth, + 46 of Mars, a + 86 of the small planets, 

 + 166 of Jupiter, o+ 326 of Saturn, and a + 646 of Uranus. The law 

 foils, however, in the case of Neptune, the distance of which is a + 99 6, 

 instead of a + 128 6. 



To convert the above relative distances into actual ones, consider the 

 distance from the Sun to the Earth as 23,984 mean semidiametera of 

 the Earth, the mean seinidiameter being 3956 miles ; so that the dis- 

 tance in question is 95 millions of miles. The semidiainctcr of the 

 sun is 111*454 times that of the earth; so that the distance of the 

 Earth from the Sun may be called 215 semidiameters of the Sun. One 

 of our objects in this article is to correct the absurd notions derived 

 from the playthings called orreries, and the diagrams exhibited in books 

 and lectures. Let the capital letter O of the type which stands at the 

 beginning of the article in this work represent the Suu ; then the Earth 

 is a speck which would need a good microscope to show it ; and its dis- 

 tance from the Sun is represented by 11 inches, or nearly two inches 

 more than the length of one of our columns. Sir John Herschel describes 

 the Solar System thus : 



I'linet. 



Sun. 



Mercury. 



V. .. . 



Earth. 



Man. 



Ceres, Ac. 



Jupiter. 



Saturn. 



Uranus. 



N. : i M 



Object which represent* it. 



Globe of 4 feet diameter. 



Grain of mustard seed. 



Apea. 



A pea. 



A rather largo pin's head. 



Grains of sand. 



A moderate sized orange. 



A small orange. 



A full sized cherry, or small 



plum. 

 A good sized plum. 



Representative of It* 

 distance from the Sun. 



164 feet. 



284 feet. 



430 feet. 



654 feet 



1000 to 1200 feet. 



Half a mile. 



{ of a mile. 



A mile and a half. 



Two miles and a half. 



The txttntricily of a planet means the fractional part of a planet's 

 mean distance by which its greatest or least distance exceeds or falls 

 short of the mean distance. Arranging the larger planets in the order of 

 their excentricities, we hare 



tfor Venus . -007 



. ptune -009 



Earth . *017 



onus . -047 

 Jupiter . -048 

 Saturn . *056 



For Mars . *093 

 Mercury '206 



That is, if the mean distance of Venus were called 1000, its greatest 

 distance would be only 1007, and its least 993. 



For the excentricities of the minor planets, see AsTKltoiDS. 

 We now give a table for the times of revolution, similar to that given 

 for the distances : 



100 



255 



415 



781 



1911 



4925 



11950 



(4880 



(8060 



39 



100 



163 



306 



748 



1929 



46SO 



13G60 



26781 



24 



62 



100 



188 



460 



1186 



2878 



8401 



16400 



13' 



S3 



63 



100 



245 



631 



1531 



4467 



6 

 14 



21 



42 



100 



257 



624 



1824 



624 



20 



52 



84 



159 



388 



1000 



2488 



7082 



13770 



8 



21 

 35 

 65 



160 



412 



1000 



2918 



.1740 



3 

 7 



II 

 M 



65 



141 



343 



1000 



IMS 



2 

 4 



6 



11 



66 



1U3 



489 



1000 



The explanation of this table resembles that of the preceding one 

 times, instead of distances, being the objects of comparison. Tim*, if 

 a revolution of Jupiter contain 1000 parts of time, that of Saturn \\.f 

 2428 such parts ; and the revolution of Uranus is 84 01 as long a* that 

 of the Earth. 



In the following table will be seen the absolute time of revolution 

 in days of each planet, and also numbers expressive of the intervals (in 

 days) between two successive conjunctions with the Sun : 



Rev. 



88 

 225 

 365 



Int. of | 

 Conj. 



116 

 534 



U.v. 



687 

 1681 

 4333 



Int. of 

 Conj. 



780 

 467 

 399 



Rev. 



Int. of 

 Conj. 



M7.1l' 378 

 30687 

 59860 368 



Thus, Venus revolves in 225 days (all the numbers in this article are 

 more roughly given than in the articles specially devoted to the planets) ; 

 U in conjunction with the Sun at intervals of 584 days ; and, with iU 

 mean motion, would describe 274 in the heavens while Jupiter describes 

 23*1. Saturn moves 2*01 minutes doily ; the Earth, 59' 8"*3. 



The minor elements (in a general consideration) may be best described 

 by diagrams ; the inclinations of the orbits may be represented by the 

 following lines, which show the slope or inclination of each orbit to the 

 orbit of the Earth or plane of the ecliptic. None of the old planets have 

 an inclination of more than 7, while in the new planets the same element 

 varies from 40' (Massilia) to 35" (Pallas). 



In the next figure the plane of the ecliptic is represented : A B is the 

 line which points to the astronomical first point of Aries, or the vernal 

 equinox, and the arrows represent the directions of the planetary 



motions. On the outer circle are represented the longitudes of the 

 ascending nodes of the larger planets, or the lines in which they are 



