Page:Popular Science Monthly Volume 90.djvu/919

 Prospecting the Skies

More discoveries in astronomy are now made in a single night than all the earlier astronomers made collectively

By Dr. C. Furness

Professor of Astronomy in Vassar College

��WITH only our eyes to help us, we would know no more about the stars than did the ancient Greeks. What we need is an artificial eye — some- thing to be placed in front of our own, something which, by gathering the light reflected from distant bodies, brings those bodies miraculously nearer to us. Because Galileo was the first to employ such arti- ficial aid in astronomy, he still lives in the popular mind as the greatest of all astron- omers. It is indeed wonderful what Galileo actually succeeded in discovering with his artificial eye — a telescope which had lenses no bigger than those of a pair of spectacles. But the discoveries — using the word in its broadest sense — made by the modern astronomer are in every way as startling, in every way as important as those it was the privilege of the great Italian to record. If the modern astron- omer's explorations are not so well-known, it is because they are so extraordinarily numerous, and because they have lost in consequence something in dramatic novelty. Only a revelation of unprecedented im-

���Comet-seeking tele- scope attached to observation chair

��portance re- ceives attention in the news- papers.

Astronomers

Have Become

Specialists

The artificial eyes that we call telescopes have gained wonder- fully in power since Galileo's day. They are used more systematically, too. As- tronomers have become specialists. Some of them confine their studies to comets; others, to the planets; still others to the sun. And there are many who hardly ever look through a telescope at all, but who simply measure the positions of stars on photographic plates.

To show just how one of these specialists goes to work, let me ask you to consider the procedure of the comet-seeker. Comets usually reach their greatest brightness when they are nearest the sun, at which

���Change in the nebulosity about Nova Persei, the brilliant new star discovered in 1901. Long exposure photographs showed the star to be enveloped by an extensive nebula. A second exposure talcen weeks later showed that the nebula had expanded outward. Comparison of the portion in the white squares with reference to the three largest stars gives an idea of this expansion

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