Myths and Marvels of Astronomy
accidents on the various railway lines in a country or continent. Those
other suns which we can stars are engines working the mighty mechanism
of planetary systems, as our sun maintains the energies of our own
system; and it is a matter of some interest to us to inquire in how many
cases, among the many suns within the range of vision, destructive
explosions occur. We may take the opportunity, later, to inquire into
the number of cases in which the machinery of solar systems appears to
have broken down.
The first case of a solar conflagration on record is that of the new
star observed by Hipparchus some 2000 years ago. In his time, and indeed
until quite recently, an object of this kind was called a new star, or a
temporary star. But we now know that when a star makes its appearance
where none had before been visible, what has really happened has been
that a star too remote to be seen has become visible through some rapid
increase of splendour. When the new splendour dies out again, it is not
that a star has ceased to exist; but simply that a faint star which had
increased greatly in lustre has resumed its original condition.
Hipparchus's star must have been a remarkable object, for it was visible
in full daylight, whence we may infer that it was many times brighter
than the blazing Dog-star. It is interesting in the history of science,
as having led Hipparchus to draw up a catalogue of stars, the first on
record. Some moderns, being sceptical, rejected this story as a fiction;
but Biot examining Chinese Chronicles[32] relating to the times of
Hipparchus, finds that in 134 B.C. (about nine years before the date of
Hipparchus's catalogue) a new star was recorded as having appeared in
the constellation Scorpio.
The next new star (that is, stellar conflagration) on record is still
more interesting, as there appears some reason for believing that before
long we may see another outburst of the same star. In the years 945,
1264, and 1572, brilliant stars appeared in the region of the heavens
between Cepheus and Cassiopeia. Sir J. Herschel remarks, that, 'from the
imperfect account we have of the places of the two earlier, as compared
with that of the last, which was well determined, as well as from the
tolerably near coincidence of the intervals of their appearance, we may
suspect them, with Goodricke, to be one and the same star, with a period
of 312 or perhaps of 156 years.' The latter period may very reasonably
be rejected, as one can perceive no reason why the intermediate returns
of the star to visibility should have been overlooked, the star having
appeared in a region which never sets. It is to be noted that, the
period from 945 to 1264 being 319 years, and that from 1264 to 1572 only
308 years, the period of this star (if Goodricke is correct in supposing
the three outbursts to have occurred in the same star) would seem to be
diminishing. At any time, then, this star might now blaze out in the
region between Cassiopeia and Cepheus, for more than 304 years have
already passed since its last outburst.
As the appearance of a new star led Hipparchus to undertake the
formation of his famous catalogue, so did the appearance of the star in
Cassiopeia, in 1572, lead the Danish astronomer Tycho Brahe to construct
a new and enlarged catalogue. (This, be it remembered, was before the
invention of the telescope.) Returning one evening (November 11, 1572,
old style) from his laboratory to his dwelling-house, he found, says Sir
J. Herschel, 'a group of country people gazing at a star, which he was
sure did not exist an hour before. This was the star in question.'
The description of the star and its various changes is more interesting
at the present time, when the true nature of these phenomena is
understood, than it was even in the time when the star was blazing in
the firmament. It will be gathered from that description and from what I
shall have to say farther on about the results of recent observations on
less splendid new stars, that, if this star should reappear in the next
few years, our observers will probably be able to obtain very important
information from it. The message from it will be much fuller and more
distinct than any we have yet received from such stars, though we have
learned quite enough to remain in no sort of doubt as to their general
nature.
The star remained visible, we learn, about sixteen months, during which
time it kept its 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, except that it surpassed Sirius in
brightness and magnitude.' It appeared larger than Jupiter, which was at
that time at his brightest, and was scarcely inferior to Venus. _It did
not acquire this lustre gradually_, but shone forth at once of its full
size and brightness, 'as if,' said the chroniclers of the time, 'it had
been of instantaneous creation.' For three weeks it shone with full
splendour, during which time it could be seen at noonday 'by those who
had good eyes, and knew where to look for it.' But before it had been
seen a month, it became visibly smaller, and from the middle of December
1572 till March 1574, when it entirely disappeared, it continually
diminished in magnitude. 'As it decreased in size, it varied in colour:
at first its 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 the colour of Saturn.' All the details of
this account should be very carefully noted. It will presently be seen
that they are highly characteristic.
Those who care to look occasionally at the heavens to know whether this
star has returned to view may be interested to learn whereabouts it
should be looked for. The place may be described as close to the back of
the star-gemmed chair in which Cassiopeia is supposed to sit--a little
to the left of the seat of the chair, supposing the chair to be looked
at in its normal position. But as Cassiopeia's chair is always inverted
when the constellation is most conveniently placed for observation, and
indeed as nine-tenths of those who know the constellation suppose the
chair's legs to be the back, and _vice versa_, it may be useful to
mention that the star was placed somewhat thus with respect to the
straggling W formed by the five chief stars of Cassiopeia. There is a
star not very far from the place here indicated, but rather nearer to
the middle angle of the W. This, however, is not a bright star; and
cannot possibly be mistaken for the expected visitant. (The place of
Tycho's star is indicated in my School Star-Atlas and also in my larger
Library Atlas. The same remark applies to both the new stars in the
Serpent-Bearer, presently to be described.)
In August 1596 the astronomer Fabricius observed a new star in the neck
of the Whale, which also after a time disappeared. It was not noticed
again till the year 1637, when an observer rejoicing in the name of
Phocyllides Holwarda observed it, and, keeping a watch, after it had
vanished, upon the place where it had appeared, saw it again come into
view nine months after its disappearance. Since then it has been known
as a variable star with a period of about 331 days 8 hours. When
brightest this star is of the second magnitude. It indicates a somewhat
singular remissness on the part of the astronomers of former days, that
a star shining so conspicuously for a fortnight, once in each period of
331-1/3 days, should for so many years have remained undetected. It
may, perhaps, be thought that, noting this, I should withdraw the
objection raised above against Sir J. Herschel's idea that the star in
Cassiopeia may return to view once in 156 years, instead of once in 312
years. But there is a great difference between a star which at its
brightest shines only as a second-magnitude star, so that it has twenty
or thirty companions of equal or greater lustre above the horizon along
with it, and a star which surpasses three-fold the splendid Sirius. We
have seen that even in Tycho Brahe's day, when probably the stars were
not nearly so well known by the community at large, the new star in
Cassiopeia had not shone an hour before the country people were gazing
at it with wonder. Besides, Cassiopeia and the Whale are constellations
very different in position. The familiar stars of Cassiopeia are visible
on every clear night, for they never set. The stars of the Whale, at
least of the part to which the wonderful variable star belongs, are
below the horizon during rather more than half the twenty-four hours;
and a new star there would only be noticed, probably (unless of
exceeding splendour), if it chanced to appear during that part of the
year when the Whale is high above the horizon between eventide and
midnight, or in the autumn and early winter.
It is a noteworthy circumstance about the variable star in the Whale,
deservedly called Mira, or The Wonderful, that it does not always return
to the same degree of brightness. Sometimes it has been a very bright
second-magnitude star when at its brightest, at others it has barely
exceeded the third magnitude. Hevelius relates that during the four
years between October 1672 and December 1676, Mira did not show herself
at all! As this star fades out, it changes in colour from white to red.
Towards the end of September 1604, a new star made its appearance in
the constellation Ophiuchus, or the Serpent-Bearer. Its place was near
the heel of the right foot of 'Ophiuchus huge.' Kepler tells us that it
had no hair or tail, and was certainly not a comet. Moreover, like the
other fixed stars, it kept its place unchanged, showing unmistakably
that it belonged to the star-depths, not to nearer regions. 'It was
exactly like one of the stars, except that in the vividness of its
lustre, and the quickness of its sparkling, it exceeded anything that 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
was generally white when it was at some distance from the vapours of the
horizon.' In fact, these changes of colour must not be regarded as
indicating aught but the star's superior brightness. Every very bright
star, when close to the horizon, shows these colours, and so much the
more distinctly as the star is the brighter. Sirius, which surpasses the
brightest stars of the northern hemisphere full four times in lustre,
shows these changes of colour so conspicuously that they were regarded
as specially characteristic of this star, insomuch that Homer speaks of
Sirius (not by name, but as the 'star of autumn') shining most
beautifully 'when laved of ocean's wave'--that is, when close to the
horizon. And our own poet, Tennyson, following the older poet, sings how
the fiery Sirius alters hue,
And bickers into red and emerald.
The new star was brighter than Sirius, and was about five degrees lower
down, when at its highest above the horizon, than Sirius when _he_
culminates. Five degrees being equal to nearly ten times the apparent
diameter of the moon, it will be seen how much more favourable the
conditions were in the case of Kepler's star for those coloured
scintillations which characterised that orb. Sirius never rises very
high above the horizon. In fact, at his highest (near midnight in
winter, and, of course, near midday in summer) he is about as high above
the horizon as the sun at midday in the first week in February. Kepler's
star's greatest height above the horizon was little more than
three-fourths of this, or equal to about the sun's elevation at midday
on January 13 or 14 in any year.
Like Tycho Brahe's star, Kepler's was brighter even than Jupiter, and