RECEEATIYE SCIENCE. 



223 



nac," however, gave a more lengtliened ac- 

 count of the promised phenomenon, illus- 

 trated by a woodcut sure to catch the eye, 

 though the reader could at first hardly believe 

 it was intended to represent an expected ap- 

 pearance, so singularly near were the planets 

 placed to each other. 



A few words may here be added with ad- 

 vantage on the subject of planetary conjunc- 

 tions. The planets — that is, the principal 

 planets, not including the asteroids — run in 

 tracks very similar to each other, as viewed 

 from the earth ; but as they all appear to 

 travel with very different degrees of speed, 

 they frequently overtake each other. The 

 annexed illustration is intended to show how 



Portions of the Orbits of Jupiter and Venus. 

 the path of Jupiter runs part of its way north 

 of that of Venus, and part of its way south ; 

 also how Venus, from moving actually quicker 

 than Jupiter, and also from its being much 

 nearer than Jupiter to us who view it, will 

 traverse a portion of the celestial vault in 

 twenty days, which will occupy Jupiter nearly 

 four months. Whenever it overtakes Jupiter 

 a " conjunction" occurs ; but the curious 

 thing in the present instance was, that it 

 outran Jupiter this time, so close to the point 

 where its orbit crosses that of Jupiter, that 

 the two planets appeared to the naked eye 

 as one star. Such an occurrence was already 

 on record ; for Kepler states that, on the 9th 

 of January, 1591, he and Mcestlin witnessed 

 an occultation of Jupiter by Mars, and that 

 the red colour of the latter on that occasion 



clearly indicated that Jupiter was the further 

 of the two planets. He also mentions that, 

 on the 3rd of October, 1590, Mcestlin wit- 

 nessed an occultation of Mars by Venus. 

 On this subject, however. Professor Grant 

 remarks — " It is to be borne in mind that 

 these observations were made before the in- 

 vention of the telescope, so that it is doubtful 

 whether, in either of these cases, the one 

 planet was actually superposed above the 

 other." He adds that phenomena of a si- 

 milar nature have occurred in more recent 

 times. They are, however, extremely un- 

 usual, and this conjunction was alluded to 

 early in the year by Professor Wolfers, of 

 Berlin, as a " rare phenomenon." 



The writer was fortunate enough to see it 

 under circumstances more favourable than 

 those enjoyed by the illustrious Kepler, hav- 

 ing been one of a party of nine persons who 

 assembled in the chilly morning twilight of 

 July 21st, shortly after three o'clock a.m., 

 for the purpose of viewing the conjunction 

 through an old three-inch Dollond telescope. 

 The upper part of the sky was pretty 

 clear, and though the rapidly -increasing day- 

 light allowed but few stars to be seen, the 

 moon was bright ; but the whole eastern 

 horizon, to the height of several degrees wag 

 obscured by a reddish fog, shaded off into 

 indistinct filmy clouds. At first sight, we 

 despaired of seeing anything ; but while we 

 looked, one small star shone out in an inter- 

 stice between the clouds. It was no other 

 than our much desired planets, for this time 

 appearing as a double star of unusual compo- 

 sition. The astronomical eye-pieces of the 

 old telescope had been for some reason dis- - 

 carded by us, in an observation of the moon 

 on the preceding evening, and the terrestrial 

 eye-piece was now employed. The planets 

 were stiU half concealed by fog. Venus ap- 

 peared through the telescope of a deep yellow 

 colour, Jupiter a dull grayish white, and at 

 about this distance from each other : ^ ^,, 

 Sunrise rapidly approached ; Venus 



CI 



