CHAPTER VI.

ON NEW STARS.

To almost every eye but that of the astronomer, the starry firmament presents the same general aspect. To a common observer, the nocturnal heavens exhibit the appearance of a vast concave bespangled with countless numbers of shining points, of various degrees of brilliancy, and distributed over the sky apparently without any order or arrangement. Whether the clusters of stars which are seen in summer and in winter are the same; whether the stars which are seen in one region of the heavens at six o'clock in the morning are identically the same which are seen in the same quarter at midnight or at three in the morning; whether there be any stars which were seen by our forefathers which are no longer visible; whether any stars unknown to former generations can now be traced in the firmament, or whether any of those orbs which are visible at one time are invisible at another, to such inquiries there is not one out of a thousand of those who have occasionally gazed at the starry heavens that could give a satisfactory reply. It is the industrious astronomer alone, who, with unwearied observation, spends sleepless nights in surveying the various regions of the celestial vault, that can tell with certainty whether or not any changes occasionally take place in reference to any of the starry orbs.

The first account we have of any changes having been perceived among the stars is that recorded by Hipparchus of Rhodes, a celebrated astronomer who flourished about 120 years before the Christian era. About this period, this accurate observer of the heavens perceived, in a certain part of the firmament, a star which he had never observed before, and of which he could find no record in the observations of his predecessors. Struck with this new and unexpected phenomenon, he began to doubt whether changes might not happen among the celestial orbs as well as in the scene of nature here below. In order that such changes, when they happen, might be known to future generations, he began to form a cat

alogue of all the stars visible in that part of the world where he resided, noting down the place and apparent magnitude of each star, till he at length completed a list of all the visible stars in the heavens; which was the first catalogue of those luminaries of which we have any account in history. It is much to be regretted that we have no specific account of the particular part of the heavens where this new star appeared, as it might have led us to determine whether it be still visible, or whether it be subject to periodical changes, or have altogether disappeared.

In the year 130 after the Christian era, another new star is said to have made its appearance. In the year 389 a new star appeared near a Aquila, or Altair, in the constellation of the Eagle. Its appearance was sudden; it continued three weeks, emitting a splendour equal to that of Venus, and afterward entirely disappeared. In the ninth century a new star appeared in the fifteenth degree of Scorpio, which is said to have emitted as much light as is reflected from one quarter of the moon. In 945 a new star appeared between the constellations of Cepheus and Cassiopeia; and another, in 1264, near the constellation Cassiopeia; but of these stars the accounts are so vague and imperfect that we can form no distinct conceptions of the phenomena they exhibited.

The most striking and wonderful phenomenon of this kind, of which we have an authentic and distinct description, occurred in the beginning of November, 1572, when a new star appeared in Cassiopeia, forming nearly a rhombus with the three largest stars, a, B, y, of that constellation. Its appearance was sudden and brilliant. Its phenomena were so striking, that the sight of it determined the celebrated Tycho Brahe to become an astronomer. He did not see it at half an hour past five, when he was returning from his house to his laboratory; but returning about ten, he came to a crowd of country people who were staring at something behind him. Looking round, he saw this wonderful object. It was so bright that his staff had a shadow; it was of a dazzling white, with a little of a bluish tinge. It had no tail or hair around it similar to comets, but shone with the same kind of lustre as the other fixed stars. Its brilliancy was so great as to surpass that of Lyra and Sirius. It appeared even larger than Jupiter, which was then at its nearest approach to the earth, and by some was estimated to be superior to the

planet Venus in its greatest lustre. It was even seen by those who had good eyes at noonday; a circumstance which never happens in the case of any of the other stars, or even of the planets, except Venus, which has sometimes been seen in daylight in certain peculiar positions. During night, it was frequently seen through thin clouds which entirely intercepted the light of the other stars. In this state it continued to shine with undiminished brilliancy during the remaining part of November, or more than three weeks. It did not, however, continue much longer with this degree of brightness, but gradually diminished in its lustre. In the month of December it appeared to be only equal to Jupiter; in January, 1573, it appeared a little less than that planet, but still somewhat larger than stars of the first magnitude, to which it appeared about equal during the months of February and March; thus gradually diminishing in brightness, in April and May it was like a star of the second magnitude; in the months of June, July, and August, it was equal only to the largest stars in Cassiopeia, which are mostly of the third magnitude; in September, October, and November, it was no larger than a star of the fourth magnitude; in December, it was about equal to the star called Gamma, which was nearest to it; towards the end of 1573, and during the month of January, 1574, it was but little superior to stars of the fifth magnitude; in February it was no larger than a star of the sixth magnitude; and in the month of March it entirely disappeared, having continued visible from the beginning of November, 1572, to March, 1574, a period of about sixteen months. It was remarked that as it diminished in size it was likewise subject to certain changes in colour and brightness. When it appeared largest, its light was white and brilliant; after which it appeared a little yellowish; and in the beginning of spring, 1573, it approached something to the colour of Mars, being reddish like the star Aldebaran, or the Bull's Eye, and a little less bright than the star in the right shoulder of Orion. In the month of May that year it was of a pale livid white, like Saturn; which colour, as likewise its sparkling appearance, continued to the last, only growing more dim and faint as it approached the period of its disappearance.

Such were the appearances and changes of this wonderful star. These phenomena were particularly observed by several astronomers of that period, especially by Tycho Brahe, who

wrote a treatise on the subject, in which he determined its longitude and latitude, and demonstrated that it was situated in the region of the fixed stars, at a much greater distance from the earth than the sun, moon, or any of the planets, as it had no sensible parallax, and remained in the same point of the heavens during the whole period of its appearance. This star was likewise diligently observed by Cornelius Gemma, who says, that on the night of the 8th of November, 1572, he viewed with some attention that part of the heavens, in a very serene sky, but saw nothing uncommon; but that the next night, Nov. 9th, it appeared with a splendour surpassing all

The point in the heavens where this star appeared may be ascertained from the preceding figure, which exhibits a representation of the principal stars in Cassiopeia. The general position of this constellation may be found from the map of the circumpolar stars, Plate III. It is almost directly opposite Ursa Major, or the Great Bear. A line drawn from the Bear through the Pole-star meets Cassiopeia at nearly an equal distance on the other side of that star. When the Bear is at its lowest position below the pole, Cassiopeia is near the zenith, and vice versa. In the preceding representation (fig. 9), the large star towards the left points out the place which was occupied by the new star, which, with the three stars a, ß, y, forms a kind of rhombus or irregular square. The one on the left above the new star is ẞ, and is also known by the name of Caph. The one to the right of Caph and a little higher is a, distinguished likewise by the name Schedir. Below Schedir, and a little to the right, is the star y, or Gamma. About six degrees northwest of Caph, the telescope reveals to us a pretty large nebula of small stars, apparently compressed into one mass, with a number of loose stars surrounding it.

In the year 1604, about the end of September, another new star appeared near the heel of the right foot of Serpentarius. At that time, near the same part of the heavens, the planets Mars, Jupiter, and Saturn were very near each other, a phenomenon which so engaged the attention of astronomers that no uncommon appearance in that quarter of the heavens could long have escaped detection. On the 17th of September, Kepler, who wrote a treatise on this star, carefully observed the three planets; on the 23d he again viewed Mars and Jupiter, then approaching to their conjunction; and one of his scholars made the same observation on the 27th. On the 28th and on the 29th, which was the day when Mars and Jupiter were in conjunction, they were observed by Mastlinus and others; but none of them as yet saw anything of the new star. On the 30th the sudden breaking of the clouds afforded one of Kepler's friends an opportunity of having a very short view of it; for in looking for Mars and Jupiter, he saw a bright star near them which he had not seen before, but it was soon obscured by clouds. On the 2d, 3d, 4th, and 6th of October, it was seen by several persons in different places. On account of cloudy weather at Prague, where