Speaker 1: Section twenty three of Sun, Moon and Stars Astronomy for Beginners.
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Speaker 1: Stars Astronomy for Beginners by Agnes Gibbon, Chapter two, some
Speaker 1: particular sense, The glory of the Lord shall endure forever.
Speaker 1: The Lord shall rejoice in his works PSA. One hundred
Speaker 1: and four thirty one. In the constellation of the Swan,
Speaker 1: there is a little, dim, sixth magnitude star, scarcely to
Speaker 1: be seen without a telescope. This star, sixty one Signy
Speaker 1: by name, is the first whose distance from us it
Speaker 1: was found possible to determine. We may think it's strange
Speaker 1: that so faint a star was even attempted. Would not
Speaker 1: astronomers have naturally supposed it to be one of the
Speaker 1: farther distant stars. No, they did not, For though sixty
Speaker 1: one Sidney showed but a dim light, yet his motion,
Speaker 1: not the daily apparent motion, but the real motion at
Speaker 1: scene from Earth, was found to be so much more
Speaker 1: rapid than the motion of most other stars, that they
Speaker 1: are rightly guessed sixty one Signey to be a rather
Speaker 1: near neighbor of ours. Do not misunderstand me when I
Speaker 1: speak of more rapid motion and of rather near neighborhood.
Speaker 1: The real rate of sixty one signeys rush through space
Speaker 1: is believed to be about thirty six miles each second,
Speaker 1: or more than one thousand millions of miles each year.
Speaker 1: All we can perceive of this quick motion is that,
Speaker 1: in the course of three hundred and fifty years, sixty
Speaker 1: one Signey travels over a space in the sky about
Speaker 1: as long as the breadth of the full moon, little enough,
Speaker 1: yet far beyond that detected in the greater number of
Speaker 1: even the brightest stars. Then again, as to the near
Speaker 1: neighborhood of this star, sixty one Signy is near enough
Speaker 1: to have his distance majored. And that is saying a
Speaker 1: good deal. Alpha Century, the nearest star of which we
Speaker 1: know in the southern heavens, is more than two hundred
Speaker 1: thousand times as far distant as the Sun. But sixty
Speaker 1: one Signy, the nearest star of which we know in
Speaker 1: the northern heavens, is nearly twice as far, or some
Speaker 1: forty billions of miles away. We call sixty one Signey
Speaker 1: a star, for so he appears to common observers. In reality,
Speaker 1: instead of being only one star, the speck of light
Speaker 1: which we call sixty months Signy consists of two stars.
Speaker 1: The two are separated by a gap about half as
Speaker 1: wide again as the wide gap between the Sun and Neptune.
Speaker 1: Yet so great is their distance from us that to
Speaker 1: the naked eye the two seem to be one. These
Speaker 1: two sons might together make a sun perhaps about one
Speaker 1: third as large as Arsun. These two sons might together
Speaker 1: make a sun perhaps about one third as large as arsen.
Speaker 1: They differ in sides, the quicker movements of one showing
Speaker 1: it to be the smaller, and it is by means
Speaker 1: of their known distance from one another and their known
Speaker 1: rate of motion, that their size, or rather their weight,
Speaker 1: can be roughly calculated. Of course, neither of the two
Speaker 1: shows any actual major So much and so little is
Speaker 1: withit tolerable certainty known about this particular pair of sins. Next,
Speaker 1: let's turn to Alpha Centauri, named Alpha the first letter
Speaker 1: of the Greek alphabet, because it is the brightest star
Speaker 1: in the constellation of the Centaur, the second brightest star
Speaker 1: in a constellation is generally called Beta, the third gamma,
Speaker 1: the fourth delta, and so on, just as if we
Speaker 1: were to name them ABCD in order of brightness. The
Speaker 1: constellation Centaur lies in the southern heavens, close to the
Speaker 1: beautiful constellation called the Southern Cross, and is invisible in England.
Speaker 1: Of all the stars shining in the heavens around our Earth,
Speaker 1: two only Sirius and Cannobus show greater brilliancy than Alpha Centaury,
Speaker 1: as in the case of sixty one signy. Astronomers were
Speaker 1: laid to attempt the measurement of Alpha Centauri's distance by
Speaker 1: noticing how much more distinct were.
Speaker 2: His movements than the movements of other.
Speaker 1: Stars, though less rapid both to the eye and in
Speaker 1: reality than those of sixty one signy. The distance of
Speaker 1: Alpha Centaury from Us is more than two hundred thousand
Speaker 1: times the distance of the Sun, or about twenty millions
Speaker 1: of millions of miles. In other words, light traveling at
Speaker 1: the rate of one eighty six thousand, three hundred miles
Speaker 1: each second, takes four years to journey from Alpha Centaury
Speaker 1: to Earth, and this, so far as we yet know,
Speaker 1: is our Sun's nearest neighbor. In the heavens outside his
Speaker 1: own family circle, Alpha Centaury, like sixty one signy, is
Speaker 1: found to consist not of a single star, but of
Speaker 1: a pair of stars. It is a two sun system.
Speaker 1: Whether or no surrounded by planets cannot be told. The
Speaker 1: two sons of the Alpha Centaury double star are separated
Speaker 1: by a distance about twenty two times as great as
Speaker 1: the distance of the Earth from the Sun. Yet to
Speaker 1: the naked eye they show as a single star. Here again,
Speaker 1: one is much smaller than the other, and the smaller
Speaker 1: revolves round the larger in about eighty five years. It
Speaker 1: is supposed that the two together might form a sun
Speaker 1: considerably larger and heavier than our Sun. This belief is
Speaker 1: trendant by the great brilliancy of Alpha Centauri. Our own Sun,
Speaker 1: placed at that distance from us, would shine only about
Speaker 1: one third as brightly as he does. Turning now from
Speaker 1: the Sun whose distance was first majored, and from the
Speaker 1: nearest star with which we are acquainted, let's think about
Speaker 1: the most radiant star in the heavens, Serious, the bleazing
Speaker 1: talk star of the ancients, named by one astronomer, the
Speaker 1: King of Sins. First, as to the color of Serious,
Speaker 1: he belongs to the order of white sons. And among
Speaker 1: all the white sons known to us, Serious ranks as chief.
Speaker 1: There may be many at greater distances, far surpassing him
Speaker 1: in size and weight and brilliancy. But we can only
Speaker 1: speak so far as we know. One ancient writer spoke
Speaker 1: of Serious as a raid in you. Others followed suit,
Speaker 1: but the original epithet was probably a copyist's mystic. It is,
Speaker 1: at all events not to be depended on. Secondly, as
Speaker 1: to the distance of Serious, like a few other stars,
Speaker 1: Serious lies not quite so far away as to be
Speaker 1: beyond reach of measurement. No baseline upon Earth would cause
Speaker 1: the slightest seeming change of position in him. But as
Speaker 1: our Earth journeys round the Sun, the line from one
Speaker 1: side of her orbit to the other is found wide
Speaker 1: enough a baseline of one hundred and eighty five millions
Speaker 1: of miles does cause just a tiny seeming change. It
Speaker 1: is very little even with alpha centaury, and with Serious
Speaker 1: it is much less. The displacement of Serious is so
Speaker 1: slight that to measure his distance with exactness is impossible.
Speaker 1: Roughly calculated, Serious lies at a distance of about fifty
Speaker 1: billions of miles Arson at the distance of Sirius would
Speaker 1: shine merely as a star of the third magnitude. Light
Speaker 1: which reaches us from the Sun in nearly nine minutes
Speaker 1: and from Alpha Santauri in four years and one third,
Speaker 1: cannot reach us from Serious in much less.
Speaker 2: Than twenty years.
Speaker 1: Thirdly, as to the size of Serious, here, of course,
Speaker 1: we are in difficulties. Radiantly as Serious shines on a
Speaker 1: clear night, and dazzling as he looks through a powerful telescope,
Speaker 1: he shows no real disc or round surface.
Speaker 2: Capable of being majured.
Speaker 1: But although we cannot measure his size, we do know
Speaker 1: something of his weight and of his extraordinary brilliance. The
Speaker 1: brightness of Serious is so much greater than the brightness
Speaker 1: of our Sun would be at that same distance that
Speaker 1: it certainly seems to point to the fact of Serious
Speaker 1: being very much the larger Sun of the two. The
Speaker 1: only reliable method by which a star's probable weight can
Speaker 1: be calculated each through the discovery of a companion to
Speaker 1: the star and a knowledge of their relative distances, their
Speaker 1: times of revolution, and the speed of either. For a
Speaker 1: long while, since Sirius was not known to possess a companion,
Speaker 1: this mode of computation could not be followed like other
Speaker 1: sans Sirius has his proper motion, as it is called,
Speaker 1: an outward world through space of more than one thousand
Speaker 1: miles each minute, sometimes more, sometimes less. Mysterious irregularities in
Speaker 1: the pace of Sirius were noted as long ago as
Speaker 1: the year eighteen forty four, and by dint of careful thought,
Speaker 1: a decision was reached that some large, disturbing orb must
Speaker 1: surely belong to Sirious and revolve round him, a body
Speaker 1: large enough and near enough to exercise a disturbing influence
Speaker 1: over the greats now, hastening him on now pulling him back,
Speaker 1: even as Jupiter and Saturn by turns hurry and delay
Speaker 1: one another. There the matter rested during fully eighteen years.
Speaker 1: Then one night the dim gleam of this companion was
Speaker 1: actually seen, and having been once discovered, it was perceived
Speaker 1: again and again. So the truth of the surmise reached
Speaker 1: nearly twenty years earlier. Through simple exercise of reasoning power
Speaker 1: was proved beyond question. Although this faintly shining second star
Speaker 1: is so near to Sirius as greatly to affect the
Speaker 1: movements of the latter, disturbing his regularity of speed to
Speaker 1: an extent which could be noted forty billions of miles away.
Speaker 1: Yet the distance between Serious and his companion is somewhere
Speaker 1: about thirty seven times as great as our Earth's distance
Speaker 1: from the Sun. The dim companion appears to be in
Speaker 1: weight about equal to our sen while the bright star
Speaker 1: Sirius is not much more than twice as heavy weight. However,
Speaker 1: tells little as to size. The blazing radiance of Serious
Speaker 1: is extraordinarily compared with the dimness of his companions. Probably
Speaker 1: the latter is far cooler and consequently far denser and
Speaker 1: smaller in make, while the dazzling Serious has doubtless a
Speaker 1: photosphere of incandescent gases and glowing molten clouds like to
Speaker 1: that of Arsun, but greatly exceeding it, either in size
Speaker 1: or in actual brilliance, or probably in both. Fortunately, as
Speaker 1: to the motions of Sirius, already touched upon, it was
Speaker 1: long possible only to observe the movements of a star
Speaker 1: when he journeyed sideways across the sky. A star coming
Speaker 1: directly towards us, or passing straight away from us would
Speaker 1: always appear to be at rest. Now, however, by means
Speaker 1: of the spectroscope, it has become possible to perceive and
Speaker 1: measure the aid on motions of stars to and from
Speaker 1: our solar system, as well as their sideway journings. The
Speaker 1: sideway motion of Syrias had been discovered before, but it
Speaker 1: now appears that he does not move exactly sideways. He
Speaker 1: rushes away in a slanting direction at the rate of
Speaker 1: over one thousand millions of miles each year. Think how
Speaker 1: many millions upon millions of millions of miles he must
Speaker 1: now be farther off from us than in the years
Speaker 1: of the engine. Yet he shines on with undeemed radiance,
Speaker 1: still the most brilliant star in our sky. So small
Speaker 1: a matter are all those millions compared with the sum
Speaker 1: of his vast distance from Earth. It is an interesting
Speaker 1: fact that while Sirius is moving away from us, we
Speaker 1: are also moving away from him. Our first station ahead,
Speaker 1: which seems to lie in or near the constellation of Hercules,
Speaker 1: stands just in the opposite direction.
Speaker 2: From the goal of Serious.
Speaker 1: Fifthly has Serious a family or a system of worlds
Speaker 1: like Arson?
Speaker 2: He may have or he may not.
Speaker 1: One companion he does possess in the shape of a companion,
Speaker 1: Sin greatly inferior to himself in Leicester. Whether those two
Speaker 1: sons possess a family of revolving words, we have no
Speaker 1: power to see. If one asks why not, no reason
Speaker 1: to the contrary can be given. But to say that
Speaker 1: a thing maybe is not to say that it is.
Speaker 1: Any star in the heavens may have such a family,
Speaker 1: and any star may pursue his lonely path without an
Speaker 1: attendant near when we do not and cannot know, it
Speaker 1: is worse than useless.
Speaker 2: To be positive.
Speaker 1: Still, the discovery, after long ages of this diem huge
Speaker 1: companion too serious, And the knowledge that a very slight
Speaker 1: further increase of deemness or decrease rather of shining, would
Speaker 1: have made that companion absolutely undiscoverable by us is.
Speaker 2: Full of significance.
Speaker 1: Even a faint star at that distance can barely be detected,
Speaker 1: and a planet shining by borrowed light could not possibly
Speaker 1: become visible. Such bodies may exist in countless billions throughout space,
Speaker 1: where we see only the glimmer of a more radiant
Speaker 1: sun dotting here, and they're the vast expanse. The mere
Speaker 1: possibilities thus opened out to imagination are almost appalling. Lastly,
Speaker 1: what is serious made of. Here again the spectroscope comes
Speaker 1: to our aid. Before the discovery of spectrum analysis and
Speaker 1: its application to astronomy, astronomers can scarcely be said to
Speaker 1: have known with certainty that stars versons, and of the
Speaker 1: composition of those stars, nay even of our own sin.
Speaker 2: They were in ignorance. Now we have learned much.
Speaker 1: Now the spectroscope, by breaking up and analyzing the slender
Speaker 1: ray of light which travers earthword from each star, has
Speaker 1: shown us something of the true nature of those far
Speaker 1: off lamps of Heaven. Now I know that most of
Speaker 1: the stars, not all of them, are like our sin,
Speaker 1: great radiating machine for the giving fourth of light and
Speaker 1: heat and power.
Speaker 2: Like Arsen.
Speaker 1: Each is surrounded by a brilliant photosphere formed in a
Speaker 1: fairy atmosphere of heated and glowing gases in the white
Speaker 1: sense of which serious is king and chi. While sodium,
Speaker 1: magnesium and other metals do more or less exist, the
Speaker 1: principal component of this dazzling envelope is found to be
Speaker 1: incandescent hydrogen. Arsen belongs not to the first or Syrian
Speaker 1: class of white sens, but to the second or solar
Speaker 1: type of golden suns. In them, though hydrogen is abundant,
Speaker 1: it is not so absolutely prominent. End of Section twenty
Speaker 1: three