STARLIGHT

Press, Volume LXXII, Issue 21812, 18 June 1936, Page 5 (Supplement)

STARLIGHT

(By B. W. Collins)

What is the real shape of the universe? This is the question—or rather this is one of the questions that have been puzzling astronomers for thousands of years. Even with all our modern knowledge and wonderful instruments it still remains only partially answered. No one knows the shape of the universe as a whole, though we are fairly sure of the shape of certain parts of it. For instance, almost all the stars that can be seen with the naked eye belong to one system, and the shape of this is now pretty well agreed on among astronomers.

But telescopes have revealed objects in the sky that are many thousands of times as far away as the furthest star belonging to our own system. And there are almost certainly many others not yet discovered. How all these are arranged in space is unknown. Many of them are so far away that even their composition and structure are not definitely known. It is thought, however, that some of them at least are systems of stars similar to the one to which we belong. They are sometimes called “Island Universes,” because they are like is-

lands scattered throughout the vast sea of space. The one of which our earth is a very insignificant member is called the "Galactic System." Taken all together, these "Island Universes" comprise the universe or Cosmos (a Greek word meaning system, arrangement or world). It is about the shape of the Galactic System that we know most. First of all, it is called by this name because the Milky Way or Galaxy forms part of it. And It is the Milky Way itself that is the key to understanding is shape. It was in order to explain the exist-

THE GALACTIC SYSTEM

ence of this band of stars that the theory outlined below was first put forward. It has since been extended and tested, and is found to fit the facts better than any other explanation. Imagine a space the shape of a pikelet but thicker in the centre than at the edges. Enlarge this several million times and fill it with stars scattered more or less at random throughout the space, but slightly more densely arranged near the middle. Then you have what is thought to be the shape of our star-system. It is something like a gigantic wheel—and it :s like a wheel in more than shape merely, for it, too, is turning round its centre. The solar system (including our earth* is somewhere near the hub of the wheel—not as near as was once thought, however. In fact, it may be as far away as half-way along a spoke, or halfway between the centre and odgr of the pikelet. It is \ery close to the centre-plane of t.ie pikelet, however —that is, it is lust half-way between the top and bottom. As we look from the earth on** wjards, the rim of the wheel the edge of the pikelet* we have

to look through a much g«atf£ distance than we would u w looked sideways. Hence many more stars. But most these stars are much further This explains the Milky Way— i. ‘ composed of the innurr.f-.’ab.e away stars in the direct. on of rim of the wheel, so far away • with the naked eye we cannot them as separate points of tUP* but just all together as a cloudy brightness. All the separate •*** we see are quite close to us cu pared with those of the 541 - Way. . « Perhaps some of this article enable us, to quote Str^ Jeans, “to look at the wond«*T® panorama of the skv with a .j understanding of what means.”