conditions of the present, the last inter-glacial epoch was so mild that not only men but elephants and hippopotamuses flourished in central Europe, while at earlier times in the middle of long eras, such as the Paleozoic and Mesozoic, corals, cycads, and tree ferns flourished within the Arctic circle.
If the electro-stellar hypothesis of solar disturbances proves well founded, it may explain these peculiarities. Periods of mild climate would represent a return of the sun and the earth to their normal conditions of quiet. At such times the atmosphere of the sun is assumed to be little disturbed by sunspots, faculæ, prominences, and other allied evidences of movements; and the rice-grain structure is perhaps the most prominent of the solar markings. The earth at such times is supposed to be correspondingly free from cyclonic storms. Its winds are then largely of the purely planetary type, such as trade winds and westerlies. Its rainfall also is largely planetary rather than cyclonic. It falls in places such as the heat equator where the air rises under the influence of heat, or on the windward slopes of mountains, or in regions where warm winds blow from the ocean over cold lands.
According to the electro-stellar hypothesis, the conditions which prevailed during hundreds of millions of years of mild climate mean merely that the solar system was then in parts of the heavens where stars—especially double stars—were rare or small, and electrical disturbances correspondingly weak. Today, on the other hand, the sun is fairly near a number of stars, many of which are large doubles. Hence it is supposed to be disturbed, although not so much as at the height of the last glacial epoch.
After the preceding parts of this book had been
written, the assistance of Dr. Schlesinger made it possible to test the electro-stellar hypothesis by comparing actual astronomical dates with the dates of climatic or solar phenomena. In order to make this possible, Dr. Schlesinger and his assistants have prepared Table 6, giving the position, magnitude, and motions of the thirty-eight nearest stars, and especially the date at which each was nearest the sun. In column 10 where the dates are given, a minus sign indicates the past and a plus sign the future. Dr. Shapley has kindly added column 12, giving the absolute magnitudes of the stars, that of the sun being 4.8, and column 13, showing their luminosity or absolute radiation, that of the sun being unity. Finally, column 14 shows the effective radiation received by the sun from each star when the star is at a minimum distance. Unity in this case is the effect of a star like the sun at a distance of one light year.
It is well known that radiation of all kinds, including light, heat, and electrical emissions, varies in direct proportion to the exposed surface, that is, as the square of the radius of a sphere, and inversely as the square of the distance. From black bodies, as we have seen, the total radiation varies as the fourth power of the absolute temperature. It is not certain that either light or electrical emissions from incandescent bodies vary in quite this same proportion, nor is it yet certain whether luminous and electrical emissions vary exactly together. Nevertheless they are closely related. Since the light coming from each star is accurately measured, while no information is available as to electrical emissions, we have followed Dr. Shapley's suggestion and used the luminosity of the stars as the best available measure of total radiation. This is presumably an approximate measure of electrical activity, provided some allowance be made for disturbances by outside bodies such as companion stars. Hence the inclusion of column 14.
| [TABLE 6] | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| THIRTY-EIGHT STARS HAVING LARGEST KNOWN PARALLAXES | ||||||||||||||
| (1) Right Ascension α 1900 | (2) Declination δ 1900 | (3) Visual Mag. m | (4) Spectrum | (5) Proper Motion | (6) Radial Velocity km. per sec. | (7) Present Parallax π | (8) Maximum Parallax | (9) Minimum Distance Light Yrs. | (10) Time of Minimum Distance | (11) Magnitude at Min. Dist. | (12) Absolute Magnitude | (13) Luminosity | (14) Effective radiation at minimum distance from sun | |
| Groombr. 34 | 0h12m.7 | +43°27' | 8.1 | Ma | 2".89 | + 3 | ".28 | ".28 | 11.6 | - 4000 | 8.1 | 10.3 | 0.0063 | 0.000051 |
| [128]η Cassiop. | 43 .0 | +57 17 | 3.6 | F8 | 1 .24 | + 10 | .18 | .19 | 17.1 | - 47000 | 3.5 | 4.9 | 0.91 | 0.003110 |
| 43 .9 | +4 55 | 12.3 | F0 | 3 .01 | ..... | .24 | .... | .... | ....... | .... | 14.2 | 0.00017 | ........ | |
| [128]κ Tucanæ | 1 12 .4 | -69 24 | 5.0 | F8 | .39 | + 12 | .16 | .23 | 14.2 | -264000 | 4.2 | 6.0 | 0.33 | 0.001610 |
| τ Ceti | 39 .4 | -16 28 | 3.6 | K0 | 1 .92 | - 16 | .32 | .37 | 8.8 | + 46000 | 3.3 | 6.1 | 0.30 | 0.003840 |
| δ2 Eridani | 3 15 .9 | -43 27 | 4.3 | G5 | 3 .16 | + 87 | .16 | .22 | 14.8 | - 33000 | 3.6 | 5.3 | 0.63 | 0.002960 |
| [128]ε Eridani | 28 .2 | - 9 48 | 3.8 | K0 | .97 | + 16 | .31 | .46 | 7.1 | -106000 | 3.0 | 6.3 | 0.25 | 0.004970 |
| [128]40(0)2 Eridani | 4 10 .7 | - 7 49 | 4.5 | G5 | 4 .08 | - 42 | .21 | .23 | 14.2 | + 19000 | 4.3 | 6.1 | 0.30 | 0.001470 |
| Cordoba Z. 243 | 5 7 .7 | -44 59 | 9.2 | K2 | 8 .75 | +242 | .32 | .68 | 4.8 | - 10000 | 7.6 | 11.7 | 0.0017 | 0.000074 |
| Weisse 592 | 26 .4 | - 3 42 | 8.8 | K2 | 2 .22 | ..... | .17 | .... | .... | ....... | .... | 9.9 | 0.009 | ........ |
| [128]α Can. Maj. (Sirius) | 6 40 .7 | -16 35 | -1.6 | A0 | 1 .32 | - 8 | .37 | .41 | 8.0 | + 65000 | -1.8 | 1.2 | 27.50 | 0.429000 |
| [128]α Can. Min. (Procyon) | 7 34 .1 | + 5 29 | 0.5 | F5 | 1 .24 | - 4 | .31 | .32 | 10.2 | + 34000 | 0.5 | 3.0 | 5.25 | 0.051300 |
| [128]Fedorenko 1457-8 | 9 7 .6 | +53 7 | 7.9 | Ma | 1 .68 | + 10 | .16 | .16 | 20.4 | - 24000 | 7.9 | 8.9 | 0.023 | 0.000055 |
| Groombr. 1618 | 10 5 .3 | +49 58 | 6.8 | K5p | 1 .45 | - 30 | .18 | .23 | 14.2 | + 69000 | 6.3 | 8.1 | 0.048 | 0.000238 |
| Weisse 234 | 14 .2 | +20 22 | 9.0 | ... | .49 | ..... | .19 | .... | .... | ....... | .... | 10.4 | 0.0057 | ........ |
| Lalande 21185 | 57 .9 | +36 38 | 7.6 | Mb | 4 .78 | - 87 | .41 | .76 | 4.3 | + 20000 | 6.2 | 10.7 | 0.0044 | 0.000238 |
| Lalande 21258 | 11 0 .5 | +44 2 | 8.5 | K5 | 4 .52 | + 65 | .19 | .22 | 14.8 | - 20000 | 8.2 | 9.9 | 0.009 | 0.000041 |
| 12 .0 | -57 2 | 12.0 | ... | 2 .69 | ..... | .34 | .... | .... | ........ | ... | 14.7 | 0.00011 | ........ | |
| Lalande 25372 | 13 40 .7 | +15 26 | 8.5 | K5 | 2 .30 | ..... | .19 | .... | .... | ....... | .... | 9.9 | 0.009 | ........ |
| [128]α Centauri | 14 32 .8 | -60 25 | 0.2 | G | 3 .68 | + 22 | .76 | 1.03 | 3.2 | - 28000 | -0.5 | 4.6 | 1.20 | 0.117500 |
| [128]ξ Bootes | 14 46 .8 | +19 31 | 4.6 | K5p | .17 | + 4 | .17 | .22 | 14.8 | -598000 | 4.0 | 5.8 | 0.40 | 0.001815 |
| [128]Lalande 27173 | 51 .6 | -20 58 | 5.8 | Kp | 1 .96 | + 20 | .18 | .19 | 17.1 | - 36000 | 5.6 | 7.1 | 0.12 | 0.000412 |
| Weisse 1259 | 16 41 .4 | +33 41 | 8.4 | ... | .37 | ..... | .18 | .... | .... | ....... | .... | 9.7 | 0.011 | ........ |
| Lacaille 7194 | 17 11 .5 | -46 32 | 5.7 | K | .97 | ..... | .19 | .... | .... | ....... | .... | 7.1 | 0.12 | ........ |
| [128]β 416 | 12 .1 | -34 53 | 5.9 | K5 | 1 .19 | - 4 | .17 | .17 | 19.2 | + 21000 | 5.7 | 7.1 | 0.12 | 0.000329 |
| Argel -0.17415-6 | 37 .0 | +68 26 | 9.1 | K | 1 .33 | ..... | .22 | .... | .... | ....... | .... | 10.8 | 0.004 | ........ |
| Barnard's star | 52 .9 | + 4 25 | 9.7 | Mb | 10 .30 | - 80 | .53 | .70 | 4.7 | + 10000 | 9.1 | 13.3 | 0.0025 | 0.000114 |
| [128]70p Ophiuchi | 18 0 .4 | + 2 31 | 4.3 | K | 1 .13 | ..... | .19 | .... | .... | ....... | .... | 5.7 | 0.44 | ........ |
| [128]Σ 2398 | 41 .7 | +59 29 | 8.8 | K | 2 .31 | ..... | .29 | .... | .... | ....... | .... | 11.1 | 0.0030 | ........ |
| σ Draconis | 19 32 .5 | +69 29 | 4.8 | G5 | 1 .84 | + 26 | .20 | .23 | 14.2 | - 49000 | 4.5 | 6.3 | 0.25 | 0.001238 |
| [128]α Aquilæ (Altair) | 45 .9 | + 8 36 | 1.2 | A5 | .66 | - 33 | .21 | .51 | 6.4 | +117000 | -0.7 | 2.8 | 6.30 | 0.153600 |
| [128]61 Cygni | 21 2 .4 | +38 15 | 5.6 | K5 | 5 .20 | - 64 | .30 | .38 | 8.6 | + 19000 | 5.1 | 8.0 | 0.053 | 0.000715 |
| Lacaille 8760 | 11 .4 | -39 15 | 6.6 | G | 3 .53 | + 13 | .25 | .26 | 12.6 | - 11000 | 6.6 | 8.6 | 0.030 | 0.000189 |
| ε Indi | 55 .7 | -57 12 | 4.8 | K5 | 4 .70 | - 39 | .28 | .31 | 10.5 | + 17000 | 4.6 | 7.0 | 0.13 | 0.001230 |
| [128]Krüger 60 | 22 24 .4 | +57 12 | 9.2 | ... | .87 | ..... | .26 | .... | .... | ....... | .... | 11.3 | 0.0025 | ....... |
| Lacaille 9352 | 59 .4 | -36 26 | 7.1 | K | 6 .90 | + 12 | .29 | .29 | 11.2 | - 3000 | 7.1 | 9.4 | 0.014 | 0.000111 |
| Lalande 46650 | 23 44 .0 | + 1 52 | 8.7 | Ma | 1 .39 | ..... | .17 | .... | .... | ....... | .... | 9.9 | 0.009 | ....... |
| C. G. A. 32416 | 59 .5 | -37 51 | 8.2 | G | 6 .05 | + 26 | .22 | .22 | 14.8 | - 7000 | 8.2 | 9.9 | 0.009 | 0.000041 |
On the basis of column 14 and of the movements and distances of the stars as given in the other columns Fig. 10 has been prepared. This gives an estimate of the approximate electrical energy received by the sun from the nearest stars for 70,000 years before and after the present. It is based on the twenty-six stars for which complete data are available in Table 6. The inclusion of the other twelve would not alter the form of the curve, for even the largest of them would not change any part by more than about half of 1 per cent, if as much. Nor would the curve be visibly altered by the omission of all except four of the twenty-six stars actually used. The four that are important, and their relative luminosity when nearest the sun, are Sirius 429,000, Altair 153,000, Alpha Centauri 117,500, and Procyon 51,300. The figure for the next star is only 4970, while for this star combined with the other twenty-one that are unimportant it is only 24,850.
Figure 10 is not carried more than 70,000 years into the past or into the future because the stars near the sun at more remote times are not included among the thirty-eight having the largest known parallaxes. That is, they have either moved away or are not yet near enough to be included. Indeed, as Dr. Schlesinger strongly emphasizes, there may be swiftly moving, bright or gigantic stars which are now quite far away, but whose inclusion would alter Fig. 10 even within the limits of the 140,000 years there shown. It is almost certain, however, that the most that these would do would be to raise, but not obliterate, the minima on either side of the main maximum.
In preparing Fig. 10 it has been necessary to make