3o8 



KNOWLEDGE & SCIENTIFIC NEWS. 



[Dec, 1904. 



The Face of the Sky for December. 



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



The Sun. — On the ist the Sun rises at 7.45, and sets 

 3-t 3-53 ! on the 31st he rises at 8.S, and sets at 3.58. 



Winter commences on the 22nd, when the sun enters 

 the sign of Capricorn at 6 a.m. Solar activity is well 

 marked, and sunspots, faculae, and prominences may be 

 observed on any favourable occasion. 



For physical observations of the sun the following 

 ephemeris may be used : — 



The Moon : — 



OCCULTATIONS.- 



The Planets. — Mercury is an evening star in Sagit- 

 tarius, setting about an hour after the Sun until the 25th ; 

 he attains his greatest easterly elongation of 20-' 30' on 

 the 14th. The planet is in inferior conjunction with the 

 Sun on the 31st. 



Venus is rapidly coming into a more favourable posi- 

 tion, and towards the end of the month is well visible 

 in the evenings. On the ist she sets about 6.15 p.m., 

 and on the 31st about 7.45 p.m. The apparent diameter 

 of the planet is increasing, being 15" on the 15th, whilst 

 0-75 of the disc is illuminated. 



Mars is a morning star in \'irgo, rising about 1.38 a.m. 

 on the 15th. 



Saturn is getting more to the west and also diminish- 

 ing in brightness. About the middle of the month the 

 planet is on the meridian at sunset, and sets about 8.15 

 p.m. The ring is widely open, the diameters of the major 

 and minor axis of the outer ring being 37"-i and 9"-7 respec- 

 tively, whilst the polar diameter of the ball is i4"'8. 



Uranus is unobservable, being in conjunction with the 

 Sun on the 22nd. 



Neptune rises about 9 p.m. near the middle of the 

 month. He is situated about 14 mins. east of the 

 star n Geminorum, as will be seen on reference to the 

 chart given in the January number. The planet is 

 in opposition on the 28th, hence al)out this time he 

 souths near midnight. 



Jupiter is in a very favourable position for observa- 

 tion in the early evenings, being on the meridian about 

 8 p.m. near the middle ot the month ; also throughout the 

 month he is visible from sunset until early morning. 



The equatorial diameter of the planet on the 15th is 

 45", whilst the polar diameter is 2"-g smaller. 



The configurations of the satellites, as seen in an in- 

 verting telescope at 9 p.m., are as follows : — 



The circle (O) represents Jupiter ; signifies that the satellite is 

 on the disc ; • signifies that tiie satellite is behind the disc, or in 

 the shadow. The numbers are the numbers of the satellites. 



Meteors : — 



The principal shower of meteors during the inonth is 

 the Geminids, December loth to 12th; the radiant is in 

 R. A. VIII.'' 12'", Dec. -|- 33". The meteors are short 

 and quick, and difficult to record accurately. 



Encke's Comet was again photographed by Max Wolf 

 on October 28, when its magnitude was 12-5. 



The coinet is increasmg in brightness, being in peri- 

 helion on Jan. 4, hence it should be visible in ordinary 

 telescopes early in the month ; after the first few days, 

 however, the Moon and the comet's motion into daylight 

 will make observation impossible. 



The following ephemeris is for Berlin noon. 



Minima of Algol may be observed on the ist at 10.22 

 p.m., on the 4th at 7.1 1 p.m., 7th at 4.0 p.in., 22nd at 

 0.5 a.m., 24th at 8.54 p.m., and 27th at 5.43 p.m. 



Telescopic Objects: — 



Double Stars: — i Pegasi XXI^ 17.5"', N.u/ 20', 

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



N. 33"-ii', mags. 4-0, a-o ; 

 •17', mags. 37, 47; separa- 

 IV. 29°5o' ; mags. 5, 6'4; separa- 



T Andromedae o'^ 31.5 

 separation 36"'3. 



a Piscium P 56 9", N. 

 tion, 3"-6 



iTrianguli II^ 6.6" 

 tion 3"-5. 



Clusters: — (^ vi. 33, 34). The Perseus clusters 

 visible to naked eye and situated about midway between 

 7 Persei and 5 Cassiopeiae. These magnificent clusters 

 are described by Smyth as " affording together one of the 

 most brilliant telescopic objects in the hea\-ens." 



