THE SMALL PLANETS. 161 



THE SMALL PLANETS. 



We have already, in the general consideration^ of the 

 planetary bodies, characterized the group of small planets 

 (asteroids, planetoids, co-planets, telescopic or ultra-zodiacal 

 planets) under the name of an intermediate group, which, 

 to a certain extent, forms a zone of separation between the 

 four interior planets (Mercury, Venus, the Earth, and Mars), 

 and the four exterior -planets of our solar system (Jupiter, Sat- 

 urn, Uranus, and Neptune). Their most distinctive features 

 consist in their interlaced, greatly inclined, and extremely ec- 

 centric orbits ; their extraordinary smallness, as the diameter 

 of Vesta does not appear to equal even the fourth part of the 

 diameter of Mercury. When the first volume of the Cosmos 

 appeared (1845), only four of the small planets were known : 

 Ceres, Pallas, Juno, and Vesta, discovered by Piazzi, Olbers, 

 and Harding (between January 1, 1801, and March 29, 1807); 

 at the present time (July, 1851), the number of the small 

 planets has already increased to 14 ; they form numerically 



* Cosmos, vol. iv., p. 101. With regard to the chronology of the dis- 

 coveries of the small planets, compare p. 100 and 13] ; their relations 

 of magnitude to the meteor-asteroids (aerolites), p. 105. With respect 

 to Kepler's conjecture of the existence of a planet in the great chasm 

 between Mars and Jupiter a conjecture, however, which by no means 

 led to the discovery of the first of the small planets (Ceres), compare p. 

 Ill, 116, and 117, note t. The bitter reproach which has been thrown 

 upon a highly esteemed philosopher, " because at a time when he might 

 have known of Piazzi's discovery certainly five months before, but was 

 unacquainted with it, he denied not so much the probability, as much 

 more the necessity of a planet being situated between Mars and Jupi- 

 ter," appears to me to be little justifiable. Hegel, in his Dissertatio de 

 Orbitis Planetarum, composed in the spring and summer of 1801, treats 

 of the ideas of the ancients of the distances of the planets; and when 

 he quotes the arrangement of which Plato speaks in the Tirrueus (p. 



35, Steph.), 1.2. 3. 4. 9. 8. 27 (compare Cosmos, vol. iv., p. 



109, note t), he denies the necessity of a chasm. He says only, "Qua? 

 series si verior natures ordo sit, quam arithmetica progressio, inter quar- 

 tum et quintum locum magnum esse spatium, neque ibi planetarn de- 

 siderari apparet." " If the order of nature is more precise than an 

 arithmetical progression, there appears to be a great space between 

 the fourth and fifth place, and that no planet is required there." (He- 

 gel's VVerke, bd. xvi., 1834, p. 28; and Hegel's Leben von Rosenkranz , 

 1844, p. 154.) Kant, in his ingenious work, Naturgeschichte desHim- 

 mels, 1755, says merely that at the time of the formation of the planets, 

 Jupiter occasioned the smallness of Mars by the enormous attractive 

 force which the former possessed. He only once mentions, and then 

 in a very indecisive manner, " the members of the solar system which 

 are situated far from each other, and between which the intermediate 

 parts have not yet been discovered." Immanuel Kant, Sdmmtliche 

 Werke, th. vi., 1839, p. 87, 110, and 196.) 



