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Abelaide Ontogoya Sectory 09 Page 09
This motion, whether it is towards or away from the central, lens-shaped portion, would cause a double streaming motion in that central portion of the kind we have found in our own system. Again, and altogether apart from these considerations, there are good reasons for supposing our Milky Way to possess a double-armed spiral structure. And the great patches of dark absorbing matter which are known to exist in the Milky Way (see Fig. 22) would give very much the mottled appearance we notice in the arms (which we see edge-on) of the nebula in Coma Berenices. The hypothesis, therefore, that our universe is a spiral nebula has much to be said for it. If it be accepted it greatly increases our estimate of the size of the material universe. For our central, lens-shaped system is calculated to extend towards the Milky Way for more than twenty thousand times a million million miles, and about a third of this distance towards what we have called the poles. If, as we suppose, each spiral nebula is an independent stellar universe comparable in size with our own, then, since there are hundreds of thousands of spiral nebulae, we see that the size of the whole material universe is indeed beyond our comprehension.
Busy conquering a stubborn wilderness, the first Jamestown settlers had only a few things to make their houses cosy and cheerful. In most cases, their worldly goods consisted of a few cooking utensils, a change of clothing, a weapon or two, and a few pieces of homemade furniture. However, between 1607 and 1612, George Percy was generously outfitted with some necessities as well as much fine apparel and numerous luxury items (including a feather bed) by his brother the Ninth Earl of Northumberland, as published records of the Earl's expenditures for George show. Other persons of gentle birth and position quite probably enjoyed similar goods.
In its main lines the spectrum of a star corresponds to its colour, and we may roughly group the stars into red, yellow, and white. This is also the order of increasing temperature, the red stars being the coolest and the white stars the hottest. We might therefore imagine that the white stars are the youngest, and that as they grow older and cooler they become yellowish, then red, and finally become invisible--just as a cooling white-hot iron would do. But a very interesting recent research shows that there are two kinds of red stars; some of them are amongst the oldest stars and some are amongst the youngest. The facts appear to be that when a star is first formed it is not very hot. It is an immense mass of diffuse gas glowing with a dull-red heat. It contracts under the mutual gravitation of its particles, and as it does so it grows hotter.
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