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THE GUIDE TO NATURE 



mote part of its orbit, however, it will 

 be quite invisible both phothgraphic- 

 ally and in all existing telescopes. 



The great importance of the new 

 asteroid lies in the fact that at times 

 it approaches so near us that its ab- 

 solute distance away in miles can be 

 determined, for it draws so near that 

 when we change our position on the 

 earth it is seen to very appreciably 

 change its apparent place in the sky. 

 From this the distance in miles from 

 the earth to the sun (which is the unit 

 of distance throughout all astronomy) 

 can be determined. 



When the new asteroid was discov- 

 ered it was at the point B of its path ; 

 it was thus well past its closest ap- 

 proach to the earth, which occurred 

 just one month earlier. The asteroid 

 passes about its orbit in 4.33 years, so 

 that every four years it reaches the 

 part of its orbit which is nearest the 

 sun. It is not, however, very near the 

 earth except when the earth is near 

 the portion of its path marked A. The 

 next close approach will occur near 

 the beginning of the year 1931, and it 

 is at this time also that the little planet 

 Eros, our nearest visitor of all, will 

 approach us most closely. Soon after 

 this time the distance from the earth 

 to the sun will become known with a 

 far higher accuracy than ever before. 



It should be added that though the 

 new asteroid has been many times 

 photographed during the last few 

 weeks and though it has been ex- 

 amined with the largest telescopes, no 

 trace of the faint companion has been 

 detected. It is as yet impossible to 

 account for the announcement of the 

 discovery. The companion may have 

 a real existence (the distance apart 

 of the earth and the object is rapidly 

 increasing) or it may have been an il- 

 lusion. 



The new asteroid has now become 

 excessively faint — of only about the 

 fourteenth magnitude. When discov- 

 ered it was in the position A, Figure 

 1, but its rapid eastward motion has 

 now carried it well into Leo to the 

 position B. It is seen so high above 

 the ecliptic because the inclination of 

 the orbit plane to the plane of the 

 ecliptic is nearly nine degrees. It is 

 now moving southward among the 

 stars, however, and will soon pass be- 

 low the Celestial equator. 



The Planets in May. 



Mercury is a morning star through- 

 out the month. It will reach its great- 

 est distance west of the sun on May 

 24, when it may be seen shining in the 

 northeast for somewhat more than one 

 hour before sunrise. It will again en- 

 ter the evening sky on June 26. 



Venus remains in the morning sky 

 until next November. It is steadily 

 drawing nearer the sun, but it is still 

 a very conspicuous object in the 

 morning heavens. It rises almost due 

 east about three and one-half hours 

 before sunrise on May 1, and this time 

 is decreased to two and three-quarter 

 hours by May 31. 



Mars is on the meridian in the south 

 in the extreme western border of the 

 constellation Virgo. Its westward 

 motion ceased on April 26, and it is 

 now moving eastward among the 

 stars. Its distance from the earth in- 

 creases from seventy-six million miles 

 to ninety-six million miles during the 

 present month, and it is but sixth- 

 tenths as bright at the end as at the 

 beginning. Even when faintest, how- 

 ever, it is 1.7 times as bright as a first 

 magnitude star. 



Jupiter is moving slowly eastward 

 and northward between the Hyades 

 and the Pleiades. It may still be seen 

 in the early evening, though it is be- 

 yond the borders of our evening map. 

 It enters the morning sky on June 15, 



Saturn is moving quite rapidly 

 eastward and southward through the 

 constellation Cancer. By December 

 12 its motion will carry it within 

 thirty seconds of the star Regulus (at 

 C, Fig. 1) though it will be about a de- 

 gree north of this star. The two ob- 

 jects will then form a beautiful fig- 

 ure in the south, but after this date 

 Saturn will begin to move westward 

 again. The reader may remember that 

 some months ago Saturn was nearly 

 in a line with the Twin Stars, while 

 now it is far to the east of this line. 

 Uranus is in the morning heavens in 

 the constellation Aquarius. 



Neptune is in Gemini, sixteen min- 

 utes west of Saturn, and six minutes 

 south on May 1, and twenty-two min- 

 utes west and seventeen minutes north 

 on May 31. On May 12 it is of the 

 same declination as Saturn, and eigh- 

 teen minutes west of it. 



