Shooting stars, although noticed in former times, have only within the last half century attracted any particular attention. This branch of the science may therefore be considered to be, comparatively, in its infancy. We must possess a long and carefully made series of observations before we are likely to be acquainted, with any degree of precision, with the physical nature of these objects. They were formerly considered to be merely atmospheric meteors, caused by the combustion of inflammable gases. This opinion has, however, now lost much, if not all, of its force, and they are now recognised as bodies which, although they become inflamed on coming in contact with the Earth's atmosphere, yet have their origin far beyond it.

It is now an established fact, that there is no night throughout the year on which shooting stars may be not seen; and that, on an average, from 5 to 7 may be noticed on a clear night every hour. These occasional meteors may be termed sporadic, in contradistinction to those swarms which appear at certain times of the year, and which are periodic.