The next thing you should make sure of is, that you have not found one of our old familiar friends, the planets. If it is really a great comet coming toward the Sun, it will grow larger and brighter every night, and you will soon be able to see its tail, which is the real earmark of a really truly comet.
When a comet is nearest us its head may shine far brighter than any of the planets, and its great tail may be millions of miles in length, and spread out in a glowing arc and light up the whole sky.
When this time comes a comet is by far a greater sight to the naked eye than it is when seen through the largest telescope. You should observe the comet often and carefully, for another one may not appear for a long time.
Fig. 131.—Halley’s Comet, from Photo.
The nearer a comet gets to the Sun the faster it travels; some comets have been known to move a thousand times as fast as a rifle-ball, and this is the more surprising when we consider that the great, flaming tail goes along with it at the same terrific rate of speed.
The tails of comets do some very strange things; for example we should rather expect the tail of a comet to always follow its head like a skyrocket, but while it does so when the comet is headed toward the Sun, when the comet is passing round and shooting into space the tail turns away from the Sun, and this causes it to move ahead of the comet, as shown in [Fig. 130].
This shows that while the head of a comet obeys the laws of gravitation, the tail does not do so, but acts as if it was electrified like the Sun, when of course it would be repelled by it. [Fig. 131] is a picture of Halley’s comet of 1910.
Although a great astronomer once said that there are more comets in the sky than fishes in the sea, there have only been 1,000 comets recorded since the beginning of written history.
