The Possible-Identity of the Kiess Comet

IT is well known that the aphelia of many comets are grouped at distances which are nearly the same as those of the larger planets, and astronomers have sometimes attempted to use this fact to demonstrate the existence of a planet beyond Neptune. M. Flammarion mentions two cases—a comet which appeared in 1532 and 1661, and Turtle's 1862 comet, which is related to the Perseid meteors, and has a period of 1211/2 years. These are taken as indications of a planet at a mean distance of about 48 astronomical units. The evidence is obviously insufficient; and special interest therefore attaches to the statement that the Kiess comet (1911b) is possibly the same as 1790 I. If the identity can be established, this comet must belong to the same group as the other two, and may be regarded as strengthening their evidence as to the hypothetical planet.