3IO 



KNOWLEDGE & SCIENTIFIC NEWS. 



[Deckmber, 1905. 



The Face of the Sky for December. 



By W. Shackleton, F.R.A.S. 



The Sun. — On the ist the Sun rises at 7.46 and sets at 

 3.52 ; on the 31st he rises at 8.S and sets at 3.5S. 



The equation of time is negligible on the 25th. 



Winter commences on the 22nd, when the Sun enters 

 the sign of Capricorn at noon. Solar activity is well 

 marked, many spots of late being visible to the naked 

 eye, whilst prominences have been particularly brilliant. 



The following table gives the position, angle of the 

 Sun's axis, and the heliographic latitude and longitude 

 of the centre of the Sun's disc : — 



OCCULTATIONS ; 



Disappearance. Reappearance. 



8 M Ceti 4-4 



9 / Tauri 4'3 



10 y Tauri 3*9 



10 75 Tauri 5-3 



10 B.A.C. 1391.. .. 4'9 



1 1 Aldebaran . . i ' i 



pm. 

 5-35 

 4-49 

 4-58 

 10.3 



11.37 

 a.m. 

 2.52 



Moon's 

 Angle Age. 

 fromN 

 point. . 



263° 

 220° 

 244° 

 269° 

 '97° 



238° 



The Planets. — Mercury (Dec. i, K.A. 17'' 58"*; 

 Dec. S. 25° 26'. Dec. 31, R.A. 17'' 4"" ; Dec. S. 20° 23'). 

 Throughout the month the planet is not suitably placed 

 for observation, being in inferior conjunction with the Sun 

 on the 15th. 



Venus (Dec. i, K.A. 15'' 14"'; Dec. S. 16^ 48'. 

 Dec. 31, R.A. 17'' 53ni; Dec. S. 23'^ 23') is a morning star 

 in Scorpio, rising only a short time before the Sun, hence 

 the planet is not well placed for observation. 



Mars (Dec. i, K..\. 20'' 52"" ; Dec. S. 19 6'. Dec. 31, 

 R.A. 22'' 21"'; Dec. S. iT" 20') is a feeble object in the 

 evening sky situated in Capricorn and Aquarius, setting 

 about three hours after the Sun. 



Jupiter (Dec. r, R..\. 3I' 54m ; Dec. N. u/17'; Dec. 31, 

 R.A. 3'' 41"' ; Dec. N. i8- 41') is a brilliant object in the 

 evening sky and is describing a retrograde path in 

 Taurus. Towards the end of the month the planet will 

 be situatedahout fi vedegreesdirectly south of the I'leiades. 



The planet is very favourably situated for observation 

 before midnight, and forms with his belt-like markings 

 and bright moons a most interesting object even in very 

 small telescopes. 



The equatorial diameter of the planet on the 15111 is 

 4b"-5, whilst the polar diameter is 3"i smaller. The 



following table gives the satellite phenomena visible in 

 this country, before midnight : — 



I. Oc. D. 



III. Sh. E. 



n. Oc. D. 



L Tr. L 



I. Sh. 1. 



U. Ec. R. 



I. Tr. E. 



I I. Sh. E. 



1. Oc. D. 



1. Ec. R. 



! I. Tr. E. 



I. Sh. E. 



nil. Tr. I. 



III. Sh. I. 



III. Tr. E. 



II. Oc. D. 



III. Sh. E. 



I. Tr. I. 



I. Sh. I. 



II. Ec. R. 



II I 



5 7 



6 6 

 8 16 



8 29 



9 3 

 10 27 

 10 42 



5 27 



7 52 



4 53 



5 'O 

 5 48 

 7 15 

 7 21 

 S 19 

 9 8 

 9 59 



10 23 



11 39 



I. Oc. D. 



I. Ec. R. 



L Sh. I. 

 II. Tr. E. 

 II. Sh. E. 



1. Tr. E. 



I. Sh. E. 

 III. Tr. I. 

 II. Oc. D. 

 III. Tr. E. 

 III. Sh. I. 



I. Tr. 1. 



I. Oc. D. 



1. Ec. R. 

 II. Tr. I. 



I. Tr. I. 

 II. Sh. I 



I. Sh. I. 

 II. Tr. E. 



7 " 

 9 47 



4 52 



5 20 



6 17 



6 37 



7 5 

 9 5 



10 34 



10 41 



11 16 

 II 44 



857 

 II 43 



5 5 



6 ID 



6 19 



6 47 



7 38 



Tr. E. 

 Sh. E. 

 Sh. E. 

 Ec. R. 

 Oc. D. 

 Tr. I. 

 Tr. I. 

 Sh. I. 

 Sh. I. 

 Tr. E. 

 Tr. E. 

 Sh. E. 

 Sh. E. 

 Oc. D. 

 Ec. R. 

 Ec. D. 

 Sh. E. 

 Ec. R. 

 Ec. R. 



8 22 

 855 



9 o 



6 12 

 10 43 



7 24 



7 56 



8 42 

 857 



9 58 

 10 8 



10 55 



11 34 



6 7 

 C 57 



"Oc. D." denotes the disappearance of the Satellite behind the disc, and 

 "Oc. R." its re-appearance ; 'Tr. I." the ingress of a transit across the disc, 

 and " Tr. E." its egress ; " Sh. I." the ingress of a transit of the shadow across 

 the disc, and " Sh. E." its egress. 



Saturn (Dec. i, R. A. 2ii> 59m; Dec. S. 13° 59'. 

 Dec. 31, R. .\. 22'' Sm; Dec. S. 13" 11') is due south 

 about sunset and well placed for observation during the 

 early part of the evening ; near the middle of the month 

 he sets about 9.20 p.m. The ring, which can be seen in 

 small telescopes with moderate powers, appears well open 

 aswearelookingat anangleof lo'^jOnthe northern surface. 



Uranus is in conjunction with the Sun on the 25lh, 

 and hence is unobservable. 



Neptune (Dec. 16, R. .\. 6'' 41-"; Dec. N. 22 g') rises 

 about 5 p.m. near the middle of the month, and is due 

 south about i a.m. The planet is situated in Gemini, 

 some 6^ east of the star m Geminoruni, but in small tele- 

 scopes without setting circles, it is difficult to identify 

 from the numerous small stars in the same lield of view, 

 but he can be detected by his motion if observations are 

 made on several successive nights. The planet is in 

 opposition to the Sun on the 31st. 



Meteors : — 



The principal shower of meteors during the month 

 is the Geininids, Dec. 10 to 12; the radiant is in 

 R. A. VII'' 12'", Dec. + 33°. The mcteois are short 

 and quick, and difficult to record accurately. 



Minima of -Mgol may be observed on the 3rd at 

 10.49 p.m., the 6th at 7.38 p.m., 26th at 9.21 p.m., and 

 29th at 6.10 p.m. 



Telescopic Objects : — 



Double Stars :— 1 Pegasi XXI*" 17.5'", N. 19" 20', 

 mags. 4'5, 8-6 ; separation 36"-2. 



TT Andromeda; o*" 31. 5", N. 33' 'n', mags. 4-0, 8'o ; 

 separation 36"*3. 



a Piscium I*" 56.9"', N. 2 •17', mags. 3-7, 4-7 ; separa- 

 tion, 3"'6. 



I Trianguli 11"6.G"', N.29"'5o'; mags. 5, 6-4 ; separa- 

 tion, 3"'5. 



Clusters:- (IJI vi.33,34). The Perseus clusters visible 

 to naked eye and situated about midway between y Persei 

 and Cassiopeia . These magnificent clusters are de- 

 scribed by Smyth as "affording together one of the most 

 brilliant telescopic objects in the heaxens." 



(M. 34.) A mass of small stars about the 8th magni- 

 tude; not very compact. The cluster is just perceptible 

 to the naked eye about 5' N.W. of Algol. 



