OUR CORNER OF SPACE

Taranaki Daily News, 31 March 1934, Page 13 (Supplement)

OUR CORNER OF SPACE

“THE ETERNAL SILENCE”

(By

the Rev. B. Dudley, F.R.A.S.)

Astronomers have been driven to the conclusion that many of the strange nebulae which look like famt, misty patches on the dark sky and are often spiral in form, are in reality other universes situated at incomprehensible distances from the one to which the solar system belongs. It has been shown that the solar system, consisting of the sun and his family of planets, and all the stars that we can see with the naked eye, comprise what may be called our universe, and that the whole is framed, so to speak, within the bounds of the Milky Way; not indeed as the central picture, but rather as an inset or corner study. As everybody knows, the Milky Way, or Galaxy, is the. zone or belt of faint stars which may be seen on a dark, clear night to span the heavens. But not everybody realises that what is thus seen is but part of an enormously distant ring—a complete circle—which represents the outer edge or rim of a lensshaped or bun-shaped universe rotating upon itself. The axis of rotation is necessarily at right angles with the plane of the Galactic system. As a matter of fact, our universe is a great spiral and the Milky Way represents the enfolding coils thereof, appearing, as seen from the earth, like a belt of stars. Try to think, then, of the solar system to which we belong, the earth being but a tiny speck therein, as situated a considerable distance from the centre of this huge scheme. The solar system itself, which is no less than 7,000,000,000 miles in diameter (for that is the width of the orbit of Pluto, the remotest planet in the sun’s retinue of worlds), is but a tiny dot within such a vast spiral. From our viewpoint within the rings or coils of this spiral we can look .right through it, and out over enormous gulfs of space beyond, and can. detect, aided by the telescope, thousands of other universes infinitely far removed from our own—"islands” in space which as seen by us are but small and faint objects, though they are in reality huge systems in many instances comparable in size and constitution with our own. One of the largest of these objects, the Great Andromeda Nebula, is located at a distance from us of 900,000 light years, and it has a diameter of 42,000 light years. There is every reason to believe that this mighty nebula or galaxy, which earlier astronomers saw as a faint and fuzzy star, is a system in all respects generally similar to the Milky Way. In all probability, however, these two galaxies are larger than the average, and possess a greater number of stars within their whorls. We do not wonder at the exclamation of a noted journalist when, in view of the fact that the depths of space have now been sounded to a distance of the order of 500,000,000 light years, he said the eternal silence of these infinite spaces made him afraid. The gulfs that separate the solar system from some of the stars within even our own galactic system are so great that they cannot be measured in miles. They are commonly reckoned in “light years.” In a single year a ray of light travels six million million miles. Not long ago the most distant objects known were believed to be only 2000 light years away! But with improved means of measuring these terrible distances the known order of things has greatly enlarged itself, as it were. The word “parsec” was coined some years ago by Professor Turner — “an inelegant but convenient portmanteau word,” someone has called it—representing about 200,000 times the distance from the earth to the sun. That distance, namely 93,000,000 miles approximately, was formerly taken as a kind of astronomical standard “yard-stick” with which to measure celestial distances. The parsec, which is a little more than three and a-half light years, is now giving way to another and much longer measuring rod, since the reach of the more recent telescopes into stellar space is much greater than it was a few years ago. The series of observations and calculations which have resulted in this extension of our ideas of the scale on which the universe is built began, during the later stages of the Great War, and took place at the Mount Wilson Observatory, California. They are largely attributable to the genius of Dr. George Ellery Hale, whose powerful equipment for this class of work is unequalled anywhere. A leading London astronomer has admitted that “the Mount Wilson solar observatory alone is responsible for extending the scale of the known universe by at least a hundred times in ten years.” Dr. Hubble, another firstclass specialist, whose greatest achievements run along the lines of penetration into star distances, refers to a still greater probing into space to a distance of many millions of parsecs, while it is anticipated that the new telescope, not yet completed, will enormously increase this penetration. From hundreds of thousands of light years as representing celestial distances in 1914 we have leaped (there is no other word) to millions of parsecs in 1934. Since these distant nebulae represent external island universes far beyond the bounds of the Milky Way and are comparable in size and glory with our own universe of stars, of what overwhelming glory and grandeur is the Greater Universe which embraces the whole! Within our galaxy, it is computed there are about 300,000,000,000 suns. The solar system is understood to be about 50,000 light years from the centre of the galaxy. The diameter of the galaxy is, according to some experts, of the order of 33,000 light years, while its diameter in a direction at right angles to this is about 3300 light years, It will be seen, then, that the solar system is constantly being carried round the centre of the galaxy in a mighty curve, which takes many millions of years to complete. The sun, it should be pointed out, is but one in a great, though widelyscattered, cloud of suns. Being in the midst of this cluster, we do not see it as such, any more than an ant would recognise a clump of trees as a cluster. Let the reader select a rather flat bun and imagine a line drawn through its middle from edge to edge. Let him now mark off a point on this line roughly half way from the centre to the circumference, and he will thus indicate the place, in the bun-shaped galaxy, of the local cluster of stars of which the _ sun is a member. The approximate position of the sun in the cluster itself is not exactly on the imaginary line, but a little to one side of it. .He may now picture this great cluster being carried round as the bun turns upon its centre. Such is our tiny corner in space.