SHOOTING STARS.

Globe, Volume IX, Issue 1270, 13 April 1878, Page 3

SHOOTING STARS.

Prof. Ball, the Astronomer Royal for Ireland, gave a lecture a short time ago at the London Institution, on “ Recent additions to our knowledge of Shooting Stars.” The lecturer reminded his hearers besides the stars we see on a clear night, and besides those the telescope makes known, there are countless bodies moving through space, which even the most powerful telescope fails to reveal, till they come either in the orbit of the earth or of its atmosphere. These are what are called meteorites and shooting stars, and it is important to distinguish clearly between the two. They are alike luminous from the same cause, that of friction in passing through the atmosphere, though but few people have ever seen a meteorite falling. The number of shooting stars is infinitely greater than is usually supposed, for observers with telescopes often see them flash across the field in dimensions too small to be seen with the naked eye. We know that shooting stars undergo combustion in passing through our atmosphere. What becomes of the debris 1 The snow of the Alps, far away from furnaces, contains globules of iron, and dust that has quietly accumulated in exposed places contains them alsol It is supposed they represent some of the debris. Though we may grumble at our atmosphere in bad weather, we must recojlect it, {it least, dqeg this, it burns up these bodies that aro pelting down upon us at a rate 100 times greater than the missile of an 81-ton gun, and, but for this burning up, they would be at any rate awkward for us. In looking at the knowledge accumulated with regard to shooting stars, the first point to notice, Professor Ball says, is that certain great showers are periodical, and always come from the same part of the heavens. According to the constellation from which they appear to come, they are caned hymda, Rersaidp, Qrionids, Leonids, &o. The inference from these recurring periods is that the orbit of the earth then cuts the orbit in which a mass of these is moving. With this fact of recurrence it must be noticed that certain comets are periodical, and from a comparison of their supposed orbits with those of groups of these bodies, a connection between them is inferred' whatever may be the origin of the comets, which is not yet known. Meteorites, on the contrary, are never known to come from the direction of a comet path. If a meteorite is carefully examined, it is spen tp bp a fragment of some rock, and that of one closely analogous to our earth’s volcanic rocks. If we consider in turn the volcanic sources from which they could have come, we see the sun would have force enough to drive off fragments ; but it is hardly likely that there are solid rocks there to drive off. Jules Yerne is right, Professor Ball says, in calculating that a body driven up ixm the earth with a force

equal to six miles a second would not return. From Ceres three miles a second would be sufficient. Examining nil the planets in turn, it seems improbable that the meteorites originate from any of them. It seems much more likely that they were in former times of greater volcanic activity driven up from the earth itself, and they again, after a lapse of ages, meet the earth in its orbit. The theory that they come in from unlimited space is, Professor Ball thinks, highly improbable.