Page:Popular Science Monthly Volume 14.djvu/737

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THE INTRA-MERCURIAL PLANETS.
717

And now comes another American astronomer, Mr. Swift, who also announces that during the same total eclipse he observed simultaneously in the field of his telescope two stars, of which the one was Theta Cancri, and the other a planet shining with the luster of a star of the fifth magnitude, and whose position he estimates approximately to be, right ascension 8h. 26m. 40s. declination 18° 30' 35", a position very near to that of the star seen and determined by Mr. Watson.

The eclipse of July 29th last, one of the most remarkable of the present century for the duration of totality, was observed all along the zone of centrality (which passed across North America), by a great number of able astronomers, both American and English. Nearly all of these searched for a new star in the neighborhood of the sun, but, with the exception of the two named above, all declare that they saw nothing beyond the stars rendered momentarily visible by the obscuration of the sun's light.

Are we thence to conclude that the testimony of these two observers must be rejected? By no means. But between this and the conclusion that the two stars signalized by Watson are in fact two planets traveling between Mercury and the sun, is a long way. Of these two stars, the second, it is supposed, can not be the star Zeta Cancri, whose position is 8h. 5m. 12s. and 18° 2'.

The difference of three minutes is no doubt very great, but when we take account of the haste of observation, and the doubt expressed by the observer himself with regard to its exactness and the possible derangement of his telescope by the action of the wind, this star must not be dismissed without seeing whether or not it will explain the observations. Now, supposing an error of three minutes more or less, the position of the first star becomes 8h. 24m. and 18° 16', and this is very nearly the position of the star Theta Cancri.

All that is needed to show how probable is this explanation is to take up a celestial atlas and to locate the sun at the point where it was at the moment of the eclipse, i. e., in front of Delta Cancri (which was visible through the aureolar corona of the eclipsed sun, at its eastern margin).

We have reproduced in the figure the aspect of the heavens during totality.

1 is Mercury, 5 is Procyon,
2 is Regulus, 6 is Pollux,
3 is Mars, 7 is Castor,
4 is the sun in eclipse, 8 is Venus.

In the immediate vicinity of the sun we have inserted at the points a, b, c, the three stars Delta, Theta, and Zeta Cancri. In our opinion the two stars b and c are the ones which might have been taken for two planets by the American observers. No doubt this hypothesis is a rather bold one, but then the hastiness, the difficulty, and the vagueness of the observation justify it.