ASTRONOMICAL NOTES FOR JULY, 1881. 155 



At that time, if observed with a good telescope, it will appear in the same form 

 as the Moon does at first or last quarters, the terminator being straight and cutting 

 the disk into equal semi-circles. For the month it will be in the constellation 

 Taurus. On the morning of the 13th a line drawn from Aldebaran to the Pleiades 

 will pass through this planet, it being near Hind's variable nebula. On the 30th 

 it will be in the Milky Way, near Chacornac's variable nebula. It is receding 

 from the earth during the entire month, its apparent diameter on ist being 72" 

 and on the 31st 20". 



Mars, from the ist to the 23d, will be in Aries, and the rest of the month in 

 Taurus. On the 6th it is in conjunction with Saturn, being north 1° 5\ On 

 tiie 14th it is 33' north of Neptune. On the morning of the 2 2d it will be in 

 close conjunction with Jupiter, being only 7' or a little less than one-fourth the 

 apparent diameter of the Moon, south of that planet. Its apparent diameter is 

 slowly increasing, being 6.64" on the ist and 7.35" on the 31st. It rises a little 

 after midnight. 



Jupiter, with its four satellites, will adorn the eastern sky, rising about 5 

 hours before the Sun. It will be in the constellation Aries. Its apparent 

 Right Ascension on the ist is 3 hours 4 minutes, and on the 31st 3 hours 23 min- 

 utes. Its apparent diameter is 34" on the ist, and 37" on the 31st. The satel- 

 lites present but few phenomena of interest, except on the morning of the i6th, 

 when the third will disappear in eclipse at 2 hours, 33 minutes, 55 seconds. 



Saturn rises about midnight — a little before Jupiter. Its position is favora- 

 ble for morning observers. The Earth on the i8th is elevated above the plane of 

 the southern surface of its ring 20°. This remarkable planet is at a mean dis- 

 tance of 872,135,000 miles from the sun. It performs a revolution around that 

 orb in 10759.2 mean solar days. Its volume is 746.9 times that of the earth. 

 This planet, belted like Jupiter, is surrounded not only by eight moons, but by a 

 succession of rings that extend out in the plane of its equator 83,000 miles, the 

 inner one being transparent. The equator of this planet, unlike that of Jupiter, 

 is inclined 26° 48' to the ecliptic; hence transits, eclipses and occultations of its 

 satellites, the orbits of which for the most part lie in the plane of the equator, occur 

 but rarely. It is the rings that form the most attractive part of this planet's 

 phenomena. We may imagine how much earlier observers (with their imperfect 

 telescopes) were puzzled by these strange appendages. It was at first supposed 

 to resemble a vase, so the name of Ansae, or handles, were given to the rings in 

 certain positions by many observers. By some it was supposed to consist of three 

 bodies, the larger one in the middle. The true nature of the ring was first dis- 

 covered by Huyghens, in 1655. Nothing in the history of astronomy is more 

 encouraging than the way in which eye and mind have spanned the tremendous 

 distance which separates us from this planet. The fact that the appearance was 

 caused by a ring. was first determined by Huyghens; then a separation dividing 

 the ring into two was observed. The extreme thinness of the rings was noted by 

 Sir William Herschel, when he saw the satellites hke pearls on a silver thread. 



