urst?]

Now, if this dark nebula was previously existing in this way all round the
star which blazed up, the question naturally arises whether the nebula had
anything to do with the conflagration. Was there previously a star, either
so cold or so distant as not to be shining with appreciable light, which,
travelling through space, encountered this vast nebula, and by the
friction of the encounter was suddenly rendered so luminous as to outshine
a star of the first magnitude? The case of meteoric stones striking our
own atmosphere seems to suggest such a possibility. These little stones
are previously quite cold and invisible, and are travelling in some way
through space, many of them probably circling round our sun. If they
happen in their journey to encounter our earth, even the extremely tenuous
atmosphere, so thin that it will scarcely bend the rays of light
appreciably, even this is sufficient by its friction to raise the stones
to a white heat, so that they blaze up into the falling stars with which
we are familiar. This analogy is suggested, but we must be cautious in
accepting it; for we know so very little of the nature of nebulae such as
that of which we have been speaking. But in any case, a totally new series
of phenomena have been laid open to our study by those wonderful
photographs taken at the Yerkes Observatory and the Lick Observatory in
the few years which the present century has as yet run.

[Sidenote: Importance of new stars]

One thing is quite certain: we must lose no opportunity of studying such
stars as may appear, and no diligence spent in discovering them at the
earliest possible moment is thrown away. We have only known up to the
present, as already stated, less than a score of them, and of these many
have told us but little; partly because they were only discovered too late
(after they had become faint), and partly because the earlier ones could
not be observed with the spectroscope, which had not then been invented.
It seems clear that in the future we must not allow accident to play so
large a part in the discovery of these objects; more must be done in the
way of deliberate search. Although we know beforehand that this will
involve a vast amount of apparently useless labour, that months and years
must be spent in comparing photographic plates, or portions of the sky
itself, with one another without detecting anything remarkable, it will
not be the first time that years have been cheerfull