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Page:Popular Science Monthly Volume 65.djvu/102

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THE POPULAR SCIENCE MONTHLY.

With the sun at such a low altitude, the atmospheric disturbances and the almost complete absorption of actinic rays will preclude the possibility of securing satisfactory observations, except perhaps as to the general form of the corona. It is known that the Chilean astronomers are expecting to view the phenomenon. Further plans do not seem to be called for.

The next observable eclipse is that of August 30, 1905. It is well situated, and will be looked forward to with unusual interest. The shadow path begins at sunrise south of Hudson's Bay, enters the Atlantic Ocean a short distance north of Newfoundland, crosses northeastern Spain, northeastern Algiers and northern Tunis, passes centrally over Assuan on the Nile, and ends at sunset in southeastern Arabia. The durations on the coast of Labrador, in Spain and at Assuan, are two and a half, three and three fourths and two and three fifths minutes, respectively.

It is none too soon to form plans for observing this eclipse. In this connection, an account of the leading eclipse problems now pressing for solution may have interest for the general reader, and perhaps some usefulness to those who will plan programs of work, though the latter will prefer a more detailed article than would be justified here.

There is probably no phenomenon of nature more beautiful and impressive than a total eclipse of the sun. Every such event is of great human interest. Even the uncivilized tribes of the earth realize, crudely, the force of the scientific fact that the sun is the origin of the light, heat and other forms of energy which make life on this planet possible.

The absorbing interest taken in eclipses by astronomers is on a broader basis. Our sun is one of the ordinary stars. In size it is perhaps only an average star; or it may even be below the average. It is the only star near enough to us to show a disk. All other stars are as mathematical points, even when our greatest telescopes magnify them 3,000-fold. The point-image of a distant star includes all its details, and it must be studied as a whole, whereas the sun can be studied in geometrical detail. Our sun is likewise the only star bright enough to supply metrical standards demanded in the study of other stars. It is not too much to say that our physical knowledge of the stars would to-day be practically a blank if we had been unable to approach them through the study of our sun. If we would understand the other stars, we must first make a complete study of our own star. Several of the most interesting portions of our sun are invisible, except at times of solar eclipse. Our knowledge of the sun will be incomplete until these portions are thoroughly understood; and this is the reason why eclipse expeditions are despatched, at great expense of time and money, to occupy stations within the narrow shadow belts.