THE OCCTJLTATION OF VENUS. 629 



ASTRONOMY. 



THE OCCULTATION OF VENUS. 



On the evening of December 8th an occultation of Venus by the moon oc- 

 curred, and, as the night was beautiful and clear, the spectacle was wit- 

 nessed by a large number of our citizens. 



We reprint from the Journal of Commerce, of this city, the following de- 

 scription, and at the same time acknowledge our indebtedness for the use 

 of the cuts illustrating the occultation : 



The following diagrams illustrate the position of the planet, with refer- 

 ence to the moon, at the beginning and end of the occultation, as seen from 

 Kansas City. The arrows represent the direction of the astronomical north 

 and south; the angle which the arrows form with the column rules of the 

 paper is equal to what is known to astronomers as the parallactic angle. 

 It value is 34.3 degrees. The times given below are calculated as nearly as 

 can be done by an "amateur" astronomer without the aid of ihe instru- 

 ments necessary to a minute calculation. 



inTo. 1. 3sro. s. 



[A vexatious blunder by the eni^ruver, loo late to be remedied, makes it uecesbary to explain that the 

 white crescent repre^nts the visible portion of the moon, and the black part the in-visible portion.] 



At about ten minutes past six, the moon being about 15 degrees above 

 the horizon in the west, the position of Venus will be on the upper left of 

 the moon's dark limb, which will then begin to creep over the planet. The 

 apparent diameter of Venus is, then, 24 8 seconds of an arc; a distance which 

 the moon will describe in very nearly one minute of time. But, as seen 

 through the telescope, Venus is almost exactly half full, giving a miniature 

 representation of the moon when the latter is a week old. The bright htilf of 

 the planetary disc is that nearest the moon, and it will be covered in about 

 thirty seconds after the beginning of the occultation, though the light of the 

 planet may be partially visible to the naked eye for a very few seconds 

 more. This will be the most interesting phase of the phenomenon. The 

 dark limb of the moon may be faintly visible at the time: this will depend 

 chiefly upon the quantity of cloud vapor in the atmosphere to the southwest 

 of us. It will probably be invisible, and in that case, if the sky be clear 



