54 



THE GUIDE TO NATURE 



even in a small telescope to be covered 

 with the most beautiful markings and 

 bandings. By watching these we can 

 see how very rapidly the world is turn- 

 ing, for a marking rises at one edge, 

 is carried completely around the planet 

 and disappears at the other in a little 



move onto the planet's disc at 10 hr. 

 56 min., not emerging from it until 1 

 hr. 36 min. the next morning. Simi- 

 larly, on July 2, 9 and 18, interesting 

 occultations or transits may be ob- 

 served. 



Saturn is now in the morning sky, 



I88O 



1889 



IIP' 1 ' ^ : **' ' '- 



AEOUATOR 



— M 



1886 



18^3 



ISBS 



Figure 2. — Detailed drawings of the Planet Jupiter, showing the appearance of the Great Red Spot in 



different years. This remarkable feature first appeared on the planet in 1878 and has not even yet 



entirely faded away. It was 30,000 miles long and 7.000 miles wide. In the square figure 



masses of vapor overlying it are readily seen. The black spots marked A are the 



shadows of Jupiter's moons cast on the ball of the planet. 



less than five hours. The four bright 

 moons, as they continually move 

 around the heated ball, sometimes 

 passing behind the disc and sometimes 

 in front of it, and sometimes enter- 

 ing or leaving the planet's shadow 

 and so being darkened, are ever 

 most interesting objects of study. For 

 example, on July 16, at 9 hr. 37 min. 

 1 s. P. M. (Eastern Standard Time), 

 the third moon will disappear in 

 eclipse, emerging again from the 

 shadow at 1 1 hr. 42 min. 8s. On the 

 same evening the second moon will 



and it each morning will be seen rising 

 earlier and mounting higher in the 

 heavens by the time of sunrise, but 

 it will be many months before we will 

 see it in our evening sky. On July 1 

 it rises two and one-half hours before 

 sunrise, which time is lengthened to 

 four and one-half hours by the end of 

 the month. The planet is now in the 

 constellation Taurus, just west of the 

 Hyades ; it will remain in nearly this 

 same position throughout the year, so 

 that when by next autumn the chang- 

 ing seasons have brought this beauti- 



