Speaker 1: Section twenty five of Sun, Moon and Stars Astronomy for Beginners.
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Speaker 1: and Stars Astronomy for Beginners by Agnes Geeburn, Groups and
Speaker 1: clusters of suns. He telleth the number of the stars.
Speaker 1: He calleth them all by their names, Psalm one forty seven,
Speaker 1: line four. We have been thinking a good deal about
Speaker 1: single stars and double stars as seen from Earth. Now
Speaker 1: we have to turn our attention to groups, clusters, masses
Speaker 1: of stars in the far regions of space. Have you
Speaker 1: ever noticed, on a winter night, when the sky was
Speaker 1: clear and dotted with twinkling stars, a band of faintly
Speaker 1: glimmering light stretching across the heavens from one horizon to
Speaker 1: the other. The band is irregular in shape, sometimes broader,
Speaker 1: sometimes narrower, Here more bright, there, more dim. If you
Speaker 1: were in the southern hemisphere, you would see the same
Speaker 1: soft belt of light passing all across the southern heavens.
Speaker 1: This band or belt is called the milky Way. Sometimes
Speaker 1: it is called the stellar system or the universe. Early
Speaker 1: in this book, Mansion was made of the word universe
Speaker 1: as used in two senses. The more modern use of
Speaker 1: it for the Milky Way, or for the particular great
Speaker 1: galaxy or gathering of stars to which our sun belongs
Speaker 1: is the smaller meeting. But what is the Milky Way?
Speaker 1: Is it made up of stars? So much we know
Speaker 1: as the astronomer turns his telescope to the zone of
Speaker 1: faintly gleaming light, he finds the stars appearing behind stars
Speaker 1: in countless multitudes, and the stronger his telescope, the more
Speaker 1: the white light changes into distant stars. Our sun we
Speaker 1: believe to be one of the stars of the Milky Way,
Speaker 1: merely one star among millions of stars, merely one golden
Speaker 1: grain among the millions of sparkling gold dust grains scattered
Speaker 1: lavishly through creation, scattered not recklessly, not by chance, but placed,
Speaker 1: arranged and guided each by its maker's upholding hand. The
Speaker 1: Milky Way, the galaxy, or the universe, as it has
Speaker 1: been variously called, has great interest for astronomers. Many have
Speaker 1: been the attempts made to discover its actual size, its
Speaker 1: true shape, how many stars it contains, how far it extends.
Speaker 1: But to all such questions the only safe answers to
Speaker 1: be returned are fenced around with perhaps and maybe. There
Speaker 1: are many very remarkable clusters of stars to be seen
Speaker 1: in the heavens. Some few visible as faint spots of
Speaker 1: light to the naked eye, though the greater number are
Speaker 1: only to be seen through a telescope, either with the
Speaker 1: naked eye or in the telescopes of varying power. They
Speaker 1: show first as mere glimmers of light, which, viewed with
Speaker 1: a more powerful telescope, separate into clusters of distant stars.
Speaker 1: The most common shape of these clusters is globular to
Speaker 1: the eye, appearing simply round. Stars gather densely near the
Speaker 1: center and gradually open out to a thin scattering about
Speaker 1: the edge. Thousands of suns are often thus collected into
Speaker 1: one cluster. The clusters are to be seen in all
Speaker 1: parts of the sky, but the greater number seen to
Speaker 1: be gathered into the space covered by the Milky Way
Speaker 1: and by the famous South Magellanic clouds, some of them
Speaker 1: utifully colored, as for instance, a cluster in Tucan not
Speaker 1: visible from England, the center of which is rose colored
Speaker 1: bordered with white. No doubt it contains a large number
Speaker 1: of bright red suns surrounded by scattering of white suns.
Speaker 1: By some it is supposed that many of these clusters
Speaker 1: may be other vast galaxies of stars, more or less
Speaker 1: like the Milky Way, lying at enormous distances from us. Others,
Speaker 1: on the contrary, rather maintain that such clusters, instead of
Speaker 1: being separate universes from our own, are merely lesser star
Speaker 1: systems included within our great stellar system, and probably all
Speaker 1: traveling round some one center. For the present, this must
Speaker 1: be considered an open question. But in either case, if
Speaker 1: worlds are journeying among the suns of such a starry cluster,
Speaker 1: what sights might not be witnessed by their possible inhabitants.
Speaker 1: We do not, indeed know the distances between the separate
Speaker 1: suns of a cluster, which may be far greater than
Speaker 1: appears to us. Yet on the other hand, it may
Speaker 1: well be that there are near enough together to shed
Speaker 1: bright light on all sides of a planet revolving in
Speaker 1: their midst The planet might or might not have within
Speaker 1: view a single sun equal in apparent size to our
Speaker 1: Sun as seen from Earth. Yet thousands of lesser suns
Speaker 1: shining night and day would cause a radiance which we
Speaker 1: never enjoy. No not night. In such a world, there
Speaker 1: could be no night. Worlds in the midst of a
Speaker 1: star cluster must be regions of perpetual day, no night,
Speaker 1: no starry heaven, no sunrise lights or sunset glories, no
Speaker 1: shadow mingling with sunshine, but one continual, ceaseless blaze of brightness.
Speaker 1: We can hardly picture, even in imagination, such a condition
Speaker 1: of things. Besides star clusters, there are also nebulaie. The
Speaker 1: word nebula comes from the Latin word for cloud, and
Speaker 1: the nebulae are so named for their hazy and cloudlike appearance.
Speaker 1: It is not always easy at first sight to distinguish
Speaker 1: between nebulaie and very distant star clusters. Both have the
Speaker 1: same dim or cloudy look. In days gone by, the
Speaker 1: star clusters were often included by astronomers under the general
Speaker 1: term of nebulae, and, as with star clusters, so with
Speaker 1: many nebulaie. More powerful telescopes have shown them to be
Speaker 1: great systems or collections of innumerable stars, crowded together by
Speaker 1: vastness of distance. But although some nebulaie are really to
Speaker 1: a certain extent, much the same as star clusters. Others
Speaker 1: are entirely differ. The spectroscope, by its delicate test, proves
Speaker 1: them to consist of enormous masses of glowing gas, and
Speaker 1: not to be solid bodies at all, even in the
Speaker 1: limited sense in which we may call our sun a
Speaker 1: solid body. Whether they are on their road to become
Speaker 1: solid bodies by and by is another question. Certainly they
Speaker 1: are not so yet. By glowing gas, I do not
Speaker 1: mean burning gas, like the gas alight at a chandelier burner.
Speaker 1: For actual burning, for being consumed and wasting away an
Speaker 1: atmosphere such as ours, is necessary. The gases which compose
Speaker 1: the outer envelopes of sun and stars, and the gases
Speaker 1: which compose the whole body of many a nebula shine
Speaker 1: with intensity of glowing but not consuming heat, and this
Speaker 1: is termed incandescence. The number of nebulaie now known amounts
Speaker 1: to thousands. There are usually divided into classes according to
Speaker 1: their apparent shapes as seen from Earth. There are circular nebulaie,
Speaker 1: oval nebulaie, anular nebulaie, conical nemuli, comentary nebuli, spiral nebulaie,
Speaker 1: and nebulae of divers other descriptions. These apparent shapes would
Speaker 1: doubtless change greatly if we could look upon them from
Speaker 1: some other standpoint and at a lessened distance. Even when
Speaker 1: seen in more powerful telescopes, they often wear a totally
Speaker 1: different aspect. Many nebulae are believed to lie in incalculable distances,
Speaker 1: and the light which comes to us from them may
Speaker 1: have been hundreds of years upon its road, but opinions
Speaker 1: differ much on this question. Some astronomers place many of
Speaker 1: the nebulai as a matter of probability, far outside the
Speaker 1: vast stellar system to which we, while others believe the
Speaker 1: most of it. Not all of the gas's nebulae are
Speaker 1: included within the bounds of our own particular starry universe.
Speaker 1: Mention must be made of the great nebula in Orion.
Speaker 1: The middle star of Orion's sword handle, when carefully noted
Speaker 1: with the naked eye, can be seen to have a
Speaker 1: slightly misty aspect. This, seen in powerful telescopes, develops into
Speaker 1: a glorious nebulae, one of the grandest in our heavens.
Speaker 1: It is shown by the spectroscope to consist partly of stars,
Speaker 1: partly of glowing gas of countless suns, possibly not large
Speaker 1: in size, but great in numbers, bathed in and surrounded
Speaker 1: by a stupendous mass of glowing gas hydrogen gas, nitrogen gas,
Speaker 1: in one other gas, the nature of which we do
Speaker 1: not know. As for the size of this nebula, we
Speaker 1: are driven to conjecture, but undoubtedly it is enormous. Measurement
Speaker 1: of size is impossible where a measurement of distance cannot
Speaker 1: be accomplished. It has, however, been suggested that if a
Speaker 1: ball be imagined so huge as to fill the entire
Speaker 1: circle of our Earth's annual pathway round the Sun, one
Speaker 1: million of such vast globes of light might be less
Speaker 1: in size than the nebula in Orion. How much larger
Speaker 1: yet it may be. None can venture to say. Another
Speaker 1: famous nebula is that in Andromeda. It can be seen
Speaker 1: by the naked eye, and has been sometimes taken for
Speaker 1: a comet. The spectroscope shows this nebula to be formed
Speaker 1: seemingly not of glowing gas, but of multitudinous faint stars,
Speaker 1: so it is more akin to an ordinary star cluster.
Speaker 1: Before quitting this subject, illusion should be made to the
Speaker 1: famous Bagelinic clouds in the southern heavens. Sometimes they are
Speaker 1: called the cape clouds. They differ from other nebulae in
Speaker 1: many points, and more particularly in their apparent size. The
Speaker 1: Great cloud is about two hundred times the size of
Speaker 1: the full moon, while the small cloud is about one
Speaker 1: quarter as large. In appearance, they are not unlike two
Speaker 1: patches of the Milky Way, separated and moved to a
Speaker 1: distance from the main stream. These clouds are surrounded by
Speaker 1: a very barren portion of the heavens, containing few stars,
Speaker 1: but in themselves they are particularly rich. Seen through a
Speaker 1: powerful telescope, they are found to abound with stars. The
Speaker 1: Greater Cloud alone contains over six hundred from the seventh
Speaker 1: to the tenth magnitudes, countless tiny star points of lesser magnitudes,
Speaker 1: star clusters of all descriptions, and nearly three hundred nebulae,
Speaker 1: all crowded into this seemingly limited space. End of Section
Speaker 1: twenty five.