Meteoric astronomy: A treatise on shooting-stars, fire-balls, and aerolites

by Daniel Kirkwood

[CHAPTER XIII.]
THE ASTEROID RING BETWEEN MARS AND JUPITER.

The mean distances of the minor planets between Mars and Jupiter vary from 2·20 to 3·49. The breadth of the zone is therefore 20,000,000 miles greater than the distance of the earth from the sun; greater even than the entire interval between the orbits of Mercury and Mars. Moreover, the perihelion distance of some members of the group exceeds the aphelion distance of others by a quantity equal to the whole interval between the orbits of Mars and the earth. The Olbersian hypothesis of the origin of these bodies seems thus to have lost all claim to probability.[30] Professor Alexander's theory of the disruption of a primitive discoidal planet of great equatorial diameter, is less objectionable; still, however, it requires confirmation. But whatever may have been the original constitution of the ring,[31] its existence in its present form for an indefinite period is unquestioned. Let us then consider some of the effects of its secular perturbation by the powerful mass of Jupiter.

Portions of the ring in which the periods of asteroids would be commensurable with that of Jupiter.—The breadth of this zone is such as to contain several portions in which the periods of asteroids would be commensurable with that of Jupiter. As in the case of the perturbation of Saturn's ring by the interior satellites, the tendency of Jupiter's influence would be to form gaps or chasms in the primitive ring.

The mean distance of an asteroid whose period is 1/2 that of Jupiter	=3·2776
That of one whose period is 1/3 of Jupiter's	=2·5012
That of one whose period is 2/5 of Jupiter's	=2·8245
That of one whose period is 2/7 of Jupiter's	=2·2569
That of one whose period is 3/7 of Jupiter's	=2·9574
That of one whose period is 4/9 of Jupiter's	=3·0299

For the purpose of facilitating the comparison of these numbers with the mean distances of the asteroids and of observing whether any order obtains in the distribution of these mean distances in space, we have arranged the minor planets, in the following table, in the consecutive order of their periods:

Periods and Distances of the Asteroids.

Order of Discovery.	Name.	Distance.	Period.
8	Flora	2·2014	1193 d
43	Ariadne	2·2034	1194·6
72	Feronia	2·2654	1245·4
40	Harmonia	2·2677	1247·3
18	Melpomene	2·2956	1270·4
80	Sappho	2·2971	1271·6
12	Victoria	2·3342	1302·6
27	Euterpe	2·3468	1313·2
4	Vesta	2·3613	1325·3
84	Clio	2·3618	1325·8
30	Urania	2·3655	1328·9
51	Nemausa	2·3657	1329·0
9	Metis	2·3858	1346·0
7	Iris	2·3863	1346·5
60	Echo	2·3931	1352·2
63	Ausonia	2·3949	1353·8
25	Phocea	2·4008	1358·8
20	Massilia	2·4144	1365·5
67	Asia	2·4217	1376·5
44	Nysa	2·4234	1378·0
6	Hebe	2·4244	1379·0
83	Beatrice	2·4287	1382·5
42	Isis	2·4400	1392·2
21	Lutetia	2·4411	1393·0
19	Fortuna	2·4416	1393·5
79	Eurynome	2·4437	1395·3
11	Parthenope	2·4519	1402·4
17	Thetis	2·4737	1421·1
46	Hestia	2·5262	1466·5
89		2·5498	1487·2
29	Amphitrite	2·5544	1491·2
5	Astræa	2·5772	1511·2
13	Egeria	2·5775	1511·4
14	Irene	2·5860	1519·0
32	Pomona	2·5868	1519·6
91		2·5958	1527·5
56	Melete	2·5959	1527·7
70	Panopea	2·6129	1543·0
53	Calypso	2·6188	1548·0
78	Diana	2·6236	1555·3
23	Thalia	2·6280	1568·0
37	Fides	2·6414	1570·0
15	Eunomia	2·6436	1572·6
85	Io	2·6466	1573·0
50	Virginia	2·6491	1575·0
88	Thisbe	2·6553	1580·0
26	Proserpina	2·6561	1581·1
66	Maia	2·6635	1587·8
73	Clytie	2·6666	1590·5
3	Juno	2·6707	1594·2
75	Eurydice	2·6707	1594·2
77	Frigga	2·6719	1595·3
64	Angelina	2·6805	1603·0
34	Circe	2·6865	1608·3
58	Concordia	2·7014	1622·0
54	Alexandra	2·7123	1631·6
59	Elpis	2·7131	1632·3
45	Eugenia	2·7218	1640·1
38	Leda	2·7401	1656·8
36	Atalanta	2·7458	1662·0
71	Niobe	2·7501	1665·8
82	Alcmene	2·7547	1670·0
55	Pandora	2·7591	1674·0
41	Daphne	2·7657	1679·9
1	Ceres	2·7663	1681·0
2	Pallas	2·7696	1683·5
39	Lætitia	2·7740	1687·6
74	Galatea	2·7777	1690·9
28	Bellona	2·7785	1691·6
68	Leto	2·7836	1696·3
81	Terpsichore	2·8591	1765·7
33	Polyhymnia	2·8653	1770·6
47	Aglaia	2·8812	1786·4
22	Calliope	2·9092	1812·4
16	Psyche	2·9233	1826·0
69	Hesperia	2·9707	1871·1
61	Danaë	2·9837	1882·4
35	Leucothea	3·0040	1904·2
49	Pales	3·0825	1976·6
86	Semele	3·0909	1984·7
52	Europa	3·1000	1993·6
48	Doris	3·1094	2002·7
62	Erato	3·1297	2022·3
24	Themis	3·1431	2035·3
10	Hygeia	3·1512	2043·2
31	Euphrosyne	3·1513	2044·6
57	Mnemosyne	3·1565	2048·4
90	Antiope	3·1576	2049·4
76	Freia	3·3864	2276·2
65	Cybele	3·4205	2310·6
87	Sylvia	3·4927	2384·2

Remarks on the foregoing Table.