NA TURE 



169 



THURSDAY, DECEMBER 22, i! 



THE STAR OF BETHLEHEM. 



THE fact that a little more than a month ago the planet 

 Venus arrived at its maximum brilliancy when to 

 the west of the sun, and therefore when the planet rises 

 before the sun, has given rise to a flood of superstitious 

 fears in this country, only to be equalled in modern times 

 by that which the members of the Eclipse Expedition 

 observed in Grenada last year, and chronicled in these 

 columns, as having been met with among the semi-civilized 

 inhabitants of that island. 



In spite of School Boards and all the present stock-in- 

 trade of elementary education, perhaps partly because 

 that elementary education deals so little with natural 

 science ; and because before School Boards so many 

 children scarcely went to school at all, the planet Venus, 

 one of the most stable and the most brilliant member 

 of the solar system, is being regarded as a second appear- 

 ance of the star of Bethlehem ! 



This being the idea which ignorance has conjured up, 

 superstition next comes in to bear her part, and hence 

 very naturally all sorts of woe and desolations, the end of 

 this world being naturally included among them, have 

 been predicted, and in some places a considerable amount 

 of alarm has really arisen. Nor is this all : thousands 

 of people who ought to be able to look up pocket-books 

 and almanacs for themselves have been for the last month 

 pestering everybody who is known to possess a telescope 

 for information on the subject. 



We think it, therefore, worth while to refer to this subject, 

 for we have in this ignorant fright an additional reason, 

 which it may be worth while to dwell upon, why the young 

 population of a country like England should not be 

 allowed to grow up without some knowledge, however 

 slight, of the natural phenomena which are always being 

 unfolded around them — phenomena which will always 

 delight, instruct, and interest them if understood, but 

 which will be apt to cause alarm so long as they are 

 shrouded in mystery. 



As before stated, the brilliant body in the east which is 

 the innocent cause of all the alarm is nothing but the 

 planet Venus near that position in her orbit in which she 

 can send the greatest amount of light towards us. 



If our youngest reader will place a candle in the middle 

 of a table, and support a little ball some six or eight 

 inches away from the candle, on the same level, and then 

 retire some little distance away, to represent a spectator 

 on the earth, the reason why Venus sometimes appears to 

 the right or to the west of the sun and at other times to 

 the east or left of it will be at once clear to him, if the 

 ball be imagined to go round the candle in a direction 

 contrary to that of the hands of a watch. Further, the fact 

 that when the ball is on the other side of the candle it 

 is further away, and therefore appears smaller than it is 

 when exactly between the candle and the spectator, 

 will give a reason why in neither of these cases will 

 the maximum brilliancy be observed, because in one 

 case the planet is as far away as it can be, and in the 

 other, though the planet is as near to us as it can be, 

 it has its dark side turned towards us ; for it must be 

 Vol. XXXVII. — No. 947. 



clearly understood that Venus, like the earth, receives 

 its light from the sun, represented in our experiment 

 by the candle ; and when the spectator is on one 

 side of the little ball, representing Venus, and the 

 candle is on the other, naturally the non-illuminated 

 side of the ball alone is turned towards the spectator. 

 The period of maximum brilliancy will be when the planet 

 is to the right or left of a line adjoining the spectator and 

 the candle, and nearer the observer than the candle is. 

 When the planet is to the right of this line, and there- 

 fore to the westward of it, speaking celestially, the planet 

 must set before the sun, and therefore rise before the sun : 

 it will be a morning star. On the other hand, when to 

 the left of it, it must set after the sun, and therefore it 

 will be visible as an evening star ; and because it sets 

 after the sun it will rise after it, and therefore be invisible 

 as a morning star on account of the overpowering 

 light of the sun. We might apologize to the readers of 

 Nature for referring to such elementary astronomy as 

 this, were it not quite possible that many of them will 

 have an opportunity, if the scare continues, of showing, 

 several young minds how to make the experiment for 

 themselves. 



The accompanying diagram will show the positions ot 

 Venus and the earth for the last few months, and will 



D'a?ram showing the paths of the Earth and Venus from July 13 to December i, 

 1887; with the points of maximum brilliancy on Augrust 16 and October 28. 

 Synodic period of Venus, 58392 mean solar days. 



indicate why it was at its brightest as a morning star^ 

 on October 28, and as an evening star on August 16. 



It will be in the memory of some of our readers that on 

 the appearance of the new star observed by Tycho Brahe 

 in 1572 the general opinion was that that also was 

 the star of Bethlehem returned. It mattered little to 

 the vulgar that the latter was called " the star in the 

 East," and that the new star was nearly in the zenith, and 

 at about the same time of the year (November). 



A reference to Grant's admirable history of physical 

 astronomy will show us that such new stars were also 

 recorded in 130, 390, 945, and 1264. The authority for 

 these statements is Cyprian Leowitz, whose work was 

 published in 1573. Although his statements have been dis- 

 credited, there is nothing improbable in them. The " new 

 star " of which we have heard the most, because there 

 was a man living who was capable of chronicling and 

 more or less understanding the phenomenon, was that 

 to which we have referred above as having appeared in 

 the year 1572. This was carefully watched by Tycho 



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