230 The Planets of the Month. 



THE PLANETS OF THE MONTH. 



BY THE EEV. T. W. WEBB, E.B.A.S. 



Mercury may be seen in the morning, at the beginning of the 

 month ; but a more favourable opportunity will occur in May. 



Venus is now transferred to the other side of the Sun, and, 

 rising before him, she will be only watched by those few who 

 pursue their studies 



" Under the opening eyelids of the morn." 



They, however, will see her to advantage, as she has already 

 attained a considerable elongation from the Sun. Her greatest 

 brilliancy takes place on April 2, when, as well as for some 

 time afterwards, she may be followed, not only with the tele- 

 scope, but even with the naked eye, even till noon-day : and 

 an exquisitely beautiful object she is, when her glare is thus 

 subdued by an illuminated background. An equatorial tele- 

 scope of course renders it perfectly easy to find her at any time ; 

 but those who do not possess such an instrument will have 

 little difficulty in keeping her in view in a clear day, if she is 

 first found before sunrise, and subsequently watched from time 

 to time, without allowing, too great an interval between the 

 observations. The epoch of greatest brightness depends upon 

 two continually varying conditions — her distance from the 

 earth, and the magnitude of her phasis, that is, the proportion 

 of her illuminated surface which is turned towards us. When 

 her phasis is largest, resembling a full moon, she is so distant 

 from us, that even were she not obscured by the Sun's rays, 

 she would not be a very brilliant object ; on the other hand, 

 when she is nearest to us, we look for the most part upon her 

 unenlightened side ; and though her apparent diameter is then 

 greater than that of any other planet, her crescent is so thin 

 that the advantage gained in point of distance is lost by her 

 narrowness of illumination. There will, however, be a point, 

 which calculation will ascertain, where these two varying quan- 

 tities will combine to produce the largest apparent illuminated 

 area ; this is not at the quadrature, or half-moon phasis, as she 

 is then too distant, but when the crescent has attained a con- 

 siderable breadth. 



Jupiter is in great splendour, having been in opposition to 

 the sun on March 12, with a diameter of 4r"6, only reduced to 

 40 ' by April 1 7. His belts seem now to be becoming more 

 distinct than they have been for some time ; as usual, two, one 

 on each side of the equator, are most conspicuous, and the 

 southern asserts its customary pre-eminence. Their variations 



