OcxniiFR. 1911. 



KNOWLEDGE. 



.i')7 



The circle (O) represents Jupiter; © signifies that the 

 Satellite i.s on the disc : • signifies that the Satellite is behind 

 the disc or in the shadow. The numbers are the numbers of 

 the Satellites. 



S..\TURN : — 



Saturn may now be conveniently observed during the 

 evening, as he rises, in the E.N'.E., at 7.8 p.m. on the 1st, and 

 at 5.6 p.m. on the J 1st. The planet is a conspicuous object, 

 some distatice to the west of Aldebaran and Mars, and cannot 

 be mistal<en. The rings are well open, the outer major and 

 minor a.xes being respectively 47" and 17", and the inclination 

 of the plane of the ring to our line of vision being 21. The 

 Southern pole of the planet is presented towards the earth. 

 The planet has eight satellites : of these, Titan (magnitude S'5i 

 can be observed with a good objective of two inches aperture, 

 lapetus (magnitude 9-12) may be seen at westerly elongation 

 with a telescope of three inches aperture, which is also 

 sufficient to show Rhea (magnitude 9.51 and Tethys 

 (magnitude 10), whilst Dionc (magnitude 10'5) requires an 

 aperture of four inches. 



The three other satellites require larger telescopes since 

 their magnitude is less than 12. 



Uranus : — 



Uranus, in Sagittarius, can only be ob,served in the early 

 evening during the present month, and is too low in the sky to 

 be well seen. The planet sets about 11.14 p.m. on the first, 

 and about 9.17 p.m. on the thirty-first. It can be distin- 

 guished from neighbouring stars by its small greenish disc of 

 3i" diameters, if viewed with sufficient magnifying power. 

 After October 6th, when the planet is stationary, the motion 

 will be direct, or easterly. 



Neptune : — 



Neptune is not yet very conveniently placed for observation, 

 as he does not rise before 11 p.m. at the beginning of the 

 month, nor before 9 p.m. at the end. The planet is located in 

 Gemini, nearly midway between 68 Getninorum and 

 ■■f- Cancri. The motion is direct, or easterly, until the 28th, 

 when the planet is stationary. 



Meteors : — 



The principal shower is that having its radiant point near 

 i- Orionis, and hence known as the Orionid shower ; the 

 maximum display is froni the ISth to the 20th. 



At.Goi,. — Observable minima of Algol occur on the 12th 

 at ten p.m., and on the 15th at seven p.m. The period is 

 2'' 20" 49". 



Telescopic Objects : — 



Douiii.E St.\rs.— 7 Arietis, l''48'", N. 18° 48', magnitudes 

 4-2, 4 • 4 ; separation 8" ■ S. Easy double, with a power of 30 ; 

 the first double star telescopically observed. 



7 Andromedae l** 58", N. 41" 51', magnitudes 2-1, 4-9; 

 separation 10". The brighter component is intensely yellow, 

 whilst the other is greenish-blue. The fainter star is a binary, 

 the components of which are tiow less than half a second 

 apart. 



Nebul.^E. — The Great Nebula in .Andromeda 3lM, easily 

 visible to the naked eye, and readily distinguished by the aid 

 of an opera glass, in the neighbourhood of ■' Andromedae. 

 Seen with a three- or fonr-inch telescope, it appears as an 

 extended oval with a bright nucleus, and has often been 

 mistaken for a comet. Spectroscopic observations suggest 

 that it is built up of a vast number of stars. 



(32m) Nebtila about 2° to the South of the Great Andromeda 

 Nebula. It is fairly round and appears like a star out of 

 focus. 



(18'J) lies about the same distance North of the great 

 Andromeda Nebula that 32M does South ; it is faint, but large 

 and elliptical. 



Comets. — Observers who possess a pocket spectroscope, 

 or its equivalent, will find it of interest to examine the spectrum 

 of Comet Brooks, even if the telescope has only an aperture of 

 two or three inches. The three typical bands of cometary 

 spectra, in the yellow green, green, and blue, we re easily 

 visible under these conditions at the time of writing (September 

 16th). The slit should first be placed at the focus of the 

 telescope by observations of a bright star, the spectrum of 

 which should appear as a narrow streak when the adjustment 

 is made. The image of the comet may then be brought on 

 the slit with the aid of the finder. 



Comet Brooks (1911 c) is visible to the naked eye as a third 

 magnitude star, but with a pair of binoculars the nebulosity 

 round the nucleus may easily be seen. The comet is moving 

 on the confines of Ursa Major and Botes towards Leo and 

 at the beginning of the month is situated about 5° S of ?; and 

 Ursa Majoris, the star at the tip nf the Bear's tail. 



