iio 



THE GUIDE TO NATURE 



for a short time in the extreme south, 

 and from northern latitudes will be 

 wholly invisible. 



In the same way six thousand years 

 ago the Southern Cross was visible 

 throughout this country and even 

 throughout England corresponding re- 

 gions of the sky now visible were then 

 wholly invisible. This describes why 

 the constellations in certain parts of 

 the sky were not named or described 

 by the ancients ; they were at that time 

 so near the South Pole of the heavens 

 that thev were not visible from north- 



the present month to be well observed. 

 It will not reach its greatest elongation 

 until April 7. 



Venus is now steadily withdrawing 

 from the sun's rays into the morning 

 sky. On March 16 it will attain its 

 greatest brilliancy and will then appear 

 exactly as bright as it did on last Jan- 

 uary 5, when it shone so brilliantly in 

 the evening heavens. By the end of the 

 month it rises in the southeast fully two 

 hours before sunrise, though it will not 

 attain its greatest distance west of the 

 sun until April 21. 



Dawe3 1864- ■ 



• Green 167? 



Lowell 1894- • 



Figure 2. These drawings of the same region of Mars, made by observers with different telescopes, 

 illustrate the difficulty of seeing the faint, uncertain markings except with telescopes of the highest power. 



ern latitudes. When the great pyramid 

 of Cheops was built Alpha Draconis 

 was our Pole Star, and the central pass- 

 age of the pyramid (as well as those in 

 several others) was directed to this 

 star. 



Now our North Star is the rather 

 faint Polaris, which has the advantage, 

 however, of being very near the Pole. 

 In twelve thousand years our North 

 Star will be the magnificent blue Vega, 

 and to one accustomed to the nightly 

 view of the sky the spectacle of the 

 heavens apparently turning about this 

 star as a center would at first seem very 

 peculiar; he would soon recognize, 

 however, that it is only the direction in 

 space of the axis about which the earth 

 is rotating that is changed. The gen- 

 eral appearance of the heavens would 

 be unaltered by precession, but what 

 interesting other changes may be 

 brought about in the course of twelve 

 thousand years we cannot at all tell. 

 ***** 



The Planets in March. 



Mercury enters the evening heavens 

 on March 12 but it will hardly emerge 

 sufficiently from the sun's rays during 



Mars is in excellent position for ob- 

 servation being in opposition with the 

 sun and hence due south at midnight 

 on March 18 though it does not reach 

 its least distance from the earth until 

 three days later. Then it will be but 

 sixty-one and two-fifths millions of 

 miles away. Though a view of this 

 world is rather disappointing in a small 

 telescope yet when the conditions are 

 favorable the polar caps and the larger 

 markings can be clearly seen even with 

 a small glass. By careful attention the 

 observer may also see that this world 

 is turning around, the day on Mars be- 

 ing but thirty-seven minutes longer 

 than the day on the earth. The finer 

 markings and the so-called canals are, 

 of course, invisible except in the largest 

 telescopes. 



Jupiter and Saturn are still in excel- 

 lent position for observation, though 

 by the end of the month the former will 

 be low in the west. The former is 

 slowly moving eastward and upward, 

 the latter westward and downward, in 

 the positions shown in Figure 1. 



Uranus is in the morning sky in the 

 constellation Aquarius where it is 

 passed by Venus on April 2, Venus 



