POPULAR ASTRONOMY. 



171 



R5DUlSMl.?\5n^N6MY 



The Heavens for August. 



BY PROF. S. ALFRED MITCHELL, OF COLUM- 

 BIA UNIVERSITY. 



Though very little is heard from the 

 daily press regarding the proposed sig- 

 nals to Mars, the astronomical inter- 

 est in this planet is continually increas- 

 ing, due to the better and better posi- 

 tion each night of the planet in the sky. 

 On August 1st the bright reddish star 

 on the horizon about 9:30 P.M. is Mars. 

 On August 15th it rises at nine o'clock, 

 on the 22nd about 8:30, and at the end 

 of the month shortly before eight. 

 During the month the planet will de- 

 crease its distance from the earth enor- 

 mously, and consequently its bright- 

 ness will be much augmented. At the 

 beginning of the month, it will be 

 forty-nine millions of miles away, at 

 the middle of August this distance will 

 be decreased by six million miles and 

 at the end of the month this will be 

 still further decreased to about 38^ 

 millions of miles. The least distance 

 will take place on September 18, when 

 Mars will be about two-fifths as far 

 away as our sun is, or about 3654 mil- 

 lions of miles. By referring to the 

 diagram on the Map for July, the 

 reader may readily satisfy himself con- 

 cerning these facts by remember- 

 ing that the distance from earth 

 to sun on the diagram is 92,000,000 

 miles on the first of the month. 

 Mars has a diameter extending 9.5", 

 it is still gibbous in appearance. By 

 the middle of the month the diameter 

 has increased to 11", and by the end of 

 the month to 12". The increase in di- 

 ameter brings with it a corresponding 

 increase in brightness, of course caused 

 by the lessening- distance from the 

 earth. 



Observations on Mars do not re- 

 quire the largest telescope in the world 

 for very excellent work may be done 

 by glasses of moderate size. Map 



making of Mars began about 1840 by 

 Beer and Maedler. The improvement 

 in refracting telescopes about this time, 

 mainly through the work of Fraun- 

 hofer in Germany, rendered better 

 drawings possible through increase of 

 optical power. By 1867, the appear- 

 ance of Mars was well known from the 

 measures of the "eagle-eyed Dawes," 

 of England, and a map by Richard A. 

 Proctor tells us of the configuration of 

 the planet. Forty years ago, it was 

 thought that the dark portions on 

 Mars were water, great oceans and 

 seas covering about three-eighths of 

 the planet, and that the lighter colored 

 areas were dry land. The white 

 patches around the north and south 

 poles were evidently polar ice caps. 

 This reasoning by analogy from what 

 is seen on the earth, it was agreed that 

 Mars was a miniature earth, and that 

 its ruddy appearance was due to an 

 abundant supply of water vapor in its 

 atmosphere. There seemed to be no 

 reason then why Mars should not be 

 inhabited by people very much resem- 

 bling those on our own planet. 



The remarkable discoveries of Schia- 

 parelli in 1877 lent a new interest to 

 the planet. In the transparent skies 

 of Italy, this excellent astronomer saw 

 markings on Mars never before de- 

 tected by human eyes. Running from 

 the so-called seas into the continents 

 were thin, more or less straight mark- 

 ings, which resembled an estuary or 

 river. These he called by the Italian 

 name "Canali," or channels, and he 

 likened them in appearance to the Eng- 

 lish Channel. Schiaparelli saw a chan- 

 nel here and another there till there 

 seemed to be a network all over the 

 planet. These markings were caught 

 sight of by using a small telescope 

 but eight inches in diameter. Other 

 astronomers with much larger glasses 

 and recognized as being as keen-eyed 



