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No part of the universe gives fuch enlarged ideas of the structure and magnificencc.of the heavens, as the consideration of the number, magnitude, and distance of the fixed stars
We admire indeed, with propiiety, the vast bulk of our own globe; but when we consider how much it is furpassed by most of the heavenly bo
little more even the vast orbit in which it revolves would appear, w hen seen from some of the fixed stars, we begin to conceive more just ideas of the extent of the universe, and the boundaries of creation.
The most conspicuous and brightest of the fixed stars of our horizon is Sirius. The earth, in moving round the fun, is 190 millions of miles, nearer to this star in one part of it's orbit, than in the opposite; yet the magnitude of the star does not appear to be in the leife altered, or it's distance affected by it; so that the distance of the fixed stars is great beyond all computation. The unbounded space appears silled at proper distances wrirh these stars, each of which is probably a fun, with attendant planets rolling round it. In this, view, what, and how amazing, is the structure of the universe!
Though the fixed stars are the only marks by which astronomers are enabled to judg'e of the course of the moveable ones,, and we have asserted
dies, what a point it de;
their relative positions do not vary; yet this assertion must be consined within some limits, for many of them are found to undergo particular changes, and perhaps the whole are liable to some peculiar motion, which connects them with the univerfal system of created nature. Dr. Herschel even goes so far as to suppose, that there is not, in strictness of speaking, one fixed star in the heavens; but that there is a general motion of all the starry systems, and consequently of the solar one among the rest.
There are some stars, whose situation and place were heretofore known, and marked with precision, that are no longer to be seen; new ones have also been discovered, that were unknown to the ancients, while numbers seem gradually to vanish. There are others which are found to have a periodical increase and decrease of magnitude; and it is probable, that the instances of these changes would have been more numerous, if the ancients had possessed the fame accurate means of examining the heavens, as are used at present.
New stars offer to the mind a phenomenon more surprizing, and less explicable, than almost any other in the science of astronomy; I shall select a sew instances of the more remarkable ones, for your instruction: a consideration of the changes that take place, at so immense a distance as the stars are known to be from you, may elevate your mind to consider the immensity of His power, who regulates and governs all these wide extended motions; "who hath measured the waters in the hollow of his hand, and meted out heaven with a span."
"Who turns his eye, on nature's midnight face,
Jbut Must Inquire What hand behind the
P 3 What
What Arm Almighty, put these wheeling globes In motion, and wound up the vast machine?"
It was a new star discovered by Hipparchus, the chief of the ancient astronomers, that induced him to compose a catalogue of the fixed stars, that future observers might learn from his labours, whether any of the known stars difappeared, or new ones were produced. The fame motives engaged the illustrious Tycho Brahe to form, with unrer mitting labour and assiduity, another new catalogue of the stars.
Of new stars, the first of which we have a good account, is that which was discovered in the constellation of Cassiopea, in the month of November of the year 1572, a time when astronomy was fufficiently cultivated, to enable the astronomers to give the account with precifion. It remained vifible about sixteen months; during this time, it kept it's place in the heavens, without the least variation. It had all the radiance of the fixed stars, and twinkled like them; and was in all respects like Sirius, excepting that it furpassed it in brightness and magnitude. ' It appeared larger than Jupiter, who was at that time in his perigee; and was scarce less bright than Venus.
It was not by degrees that it acquired this diameter, but shone forth at once of it's full size and brightness, as if of instantaneous creation. It continued about three weeks in full and entire splendor, during which time it might be seen even at noon day, by those who had good eyes, and knew where to look for it., Before it had been seen a month, it became vifibly smaller, and from thence continued diminishing in magnitude till March, 1574, when it entirely difappeared. As it decreased in size, it varied in colour; at first, it's light was white, and extremely bright;
it then became yellowish, afterwards of a ruddy colour, like Mars; and finished with a pale livid white, resembling that of Saturn.
In i 596, Fabricius observed a new star in the neck of the Whale: he first faw it in August, and it difappeared in October of the fame year. In 1637, Phocyllides Holwarda observed it again, and not knowing that it had been seen before, took it for a new discovery: he watched it's place in the heavens, and faw it appear again the succeeding year, nine months after it's difappear-' ance. It has been since found to be every year very regular in it's period, except that in 1672 it was missed by Hevclius, and not seen again till 1676. Bullialdus having compared together the observations which had been made of it from 1638 to 1666, determined the periodical time between this star's appearing in it's greatest brightness, and returning to it again, to be 333 days; observing surther, that this star did rtot appear at once in it's sull magnitude, or brightness, but by degrees arrived at them. He also framed an hypothesis, to account for these periodic changes.
Three changeable, or re-apparent stars have been discovered in the constellation of the Swan; the first was seen by Jansonius, in 1600; the second was discovered in 1670; the third by Kirchius, in 1686.
In the latter end of September, 160^, a new star was discovered near the heel of the right foot of Serpentarius. There were in that part of the heavens, at that time, the three superior planets, which so engaged the attention of astronomers, that no appearance thereabouts could have long escaped them. Kepler, in describing it, fays, that it was precisely round, without any kind of hair, or
tail; that it was exactly like one of the stars, except that in the vividness of it's lustre, and the quickness of it's sparkling, it exceeded any thing he had ever seen before. It was every moment changing into some of the colours of the rainbow, as yellow, orange, purple, and red; though it wa£ generally white, when it was at some distance from the vapours of the horizon. Those in general who saw it, agreed that it was larger than any other fixed star, or even any of the planets, except Venus: it preserved it's lustre and size for about three weeks; from this time it grew gradually smaller. Kepler supposes that it difappeared some time between October, 1605, and the February following, but on what day is uncertain.
Besides these several re-apparent stars, so well characterized and established by the earliest among the modern astronomers, there have been many discovered since, by Cassini, Maraldi, and others; Mr. Montancre speaks of having observed above one hundred changes among the fixed stars.
Proper Motion Of The Stars.
Many stars have been found to alter their position with respect to those to which they were adjacent, and this change of position has been termed the proper motion of the stars.
The proper motion of Sirius, Castor, Procyon, Pollux, Regulus, Arcturus, and Aquilæ, in 100 years in right ascension, are respectively, 1 minute, 3 seconds ; 1 minute, 28 seconds; 1 minute, 33 seconds ; 41 seconds; 2 minutes, 20 seconds; and 57 seconds. The proper motion of Sirius in declination, in a century, is 2 minutes; and of Arcturus is 3 minutes, 21 seconds, both tending to the south.'
The apparent brightness of some of the fixed stars is observed to be periodic. The star Algol,