238 



KNOWLEDGE. 



[December 1, 1892. 



THE FACE OF THE SKY FOR DECEMBER. 



By Herbert Sadler, F.R.A.S. 



DURING October and the beginning of November, 

 sunspots have been not ijiiite so plentiful and 

 large as in the spring. The following are con- 

 venientl.y observable minima of two Algol- type 

 variables : — Algol, December 2nd, 4h. Om. p.m. ; 

 December 17th, Oh. om. a.m. ; December 19th, 8h. 53m. 

 P.M. ; December 2'2nd, 5h. 42m. p.m. U Cephei, December 

 4th, 9h. 19m. f.n. ; December 9th, 8h. 58m. p.m. ; 

 December 14th, 8h. 38m. p.m. ; December 19th, 8h. 18m. 

 P.M. ; December 24th, 7h. 58m. p.m. : December 29th, 

 7h. 38m. p.m. 



Merciu'y is an evening star during the first week in 

 December, and a morning one during the last half of it. 

 but owing to his great southern declination he will be liable 

 to be obscured by mists near the horizon. He sets on the 

 1st at 4h. 52m. p.m , or one ho'.ir after sunset, with a 

 southern declination of 24'^ 52', and an apparent diameter 

 of 8i", xVw''l'S '^^ *^6 ^^^'^ being illuminated. After this 

 he rapidly approaches the Sun, being in inferior con- 

 junction on the 12th. On the 22nd he rises at 6h. 17m. 

 A.M., or Ih. 49m. before the Sun, with a southern declina- 

 tion of 19" 27', and an apparent diameter of 8-0", i^ths 

 of the disc being illuminated. On the 27tb he rises at 

 6h. 13m. A.M., or Ih. 55m. before the Sim, with a southern 

 dechnation of 20' 15', and an apparent diameter of 75", 

 -j%ths of the disc being illuminated, and the planet being 

 at his greatest brightness during the month. On the 31st 

 lie rises at 6h. 18m. a.m., or Ih. 50m. before the Sun, with 

 a southern declination of 21° 9', and an apparent diameter 

 of 6V'i TrAjtlis of the disc being illuminated. During the 

 latter half of the month Mercury describes a curved path 

 in Ophiuchus, in a region almost barren of naked eye stars. 

 Venus is a morning star, rising at 4h. IGm. a.m., or 3^ 

 hours before the Sun, witli a southern declination of 

 11' 17', and an apparent diameter of 13|" -i%ths of the 

 disc being illuminated, and her brightness being about what 

 it was at the end of last February. On the 10th she rises 

 at 5h. 3m. a.m., or 8 hours before the Sun, with a southern 

 declination of 16° 55', and an apparent diameter of 12|", 

 ^^ths of the disc being illuminated. On the 31st she 

 rises at 5h. 44m. a.m., or 2h. 24m. before the Sun, with a 

 souihern declination of 20' 59', and an apparent diameter 

 of 120", jij%ths of the disc being illuminated, and her 

 brightness being about what it was at the end of January. 

 At 7h. A.M. on the 20th a 9th magnitude star will be 26" 

 north of the planet. During the month Venus passes 

 from Virgo through Libra into Scorpio. When rising on 

 the 28rd she is about 36' «/" the 3rd magnitude star (3 

 Scorpii, and at Oh. a.m. on Christmas Day she is | of a 

 minute of time preceding and 0' south of v Scorpii, 4^ 

 magnitude, /3 being a pretty double star, and r being a 

 triple in moderate-sized telescopes ; both of the large stars 

 composing fS and v being again double in large instruments. 

 Mara is an evening star, but is rapidly getting fainter 

 and smaller, though he is h: a much sietter position as 

 regards elevation above the horizon. He sets at lib. 38m. 

 P.M. on the 1st, with a southern declination of 7° 30', and 

 an apparent diameter of 9-5", the defect of illumination on 

 the following limb being obvious. His brightness is then 

 only one-eighth of what it was at opposition. On the 16th 

 he sets at llh. 38m. p.m., with a southern declination of 

 3° 23', and an apparent diameter of 8-5". On the 31st he 

 sets at llh. 36m. p.m., with a northern declination of 

 0° 45', and an apparent diameter of 7'6", his brightness 

 being then only one-thirteenth of what it was at 

 opposition. He is in quadrature with the Sun at mid- 



night on the 9th. During December Mars describes 

 a direct path fi'om Aquarius into Pisces. At 8h. 30m. p.m. 

 on the 2nd a 9^ magnitude star will be 20" north of the 

 planet. Early on the evening of the 5th Mars will be 12' 

 south of the 4th magnitude star 4> Aquarii, and at about 

 9 p.m. on the 7th he will be 7|' north of the 5i magnitude 

 star 96 Aquarii. 



Ceres is an evening star, southing on the 14th at 9h. 35m. 

 P.M., with a northern declination of 9° 35'. At the end of 

 the mouth she is as bright as an 8th magnitude star. 

 During December she pursues a short retrograde path from 

 Taurus into the borders of Aries. At about 7h. 30m. p.m. 

 on tlie 4th she is 20' south of the 6| magnitude star 

 W'eisse's Bessel-, iiih. 275, and about 7 p.m. on the 26th 

 she is 7-5' north of and a little following the 6| magnitude 

 star B. A. C. 987. Vesta is also an evening star, southmg 

 on the 14th at 9h. 19m. p.m., with a northern declination 

 of 8^ 48'. At the end of the month she is as bright as a 

 7-J- magnitude star. During December she pursues a 

 retrograde path in Cetus, being 24' north of the 5th 

 magnitude star X Ceti at 91i. p.m. on the 16tli. 



Jupiter is an evening star, still holding his position as 

 the most magnificent object in the evening sky. On the 

 1st he rises at Ih. 47m. p.m., with a northern declination 

 of 4° 37', and an apparent equatorial diameter of 45-1", the 

 phase on the following limb being now very apparent. On 

 the 16th he rises at Oh. 47m. p.m., with a northern 

 declination of 4° 54', and an apparent equatorial diameter 

 of 43-0", the phase amounting to 0-4' . On the 31st he 

 rises at llh. 48m. a.m., and souths at 6I1. 18m. p.m., with a 

 northern declination of 5" 1', and an apparent equatorial 

 diameter of 40-9 . During the greater part of the month 

 he describes a short direct path in Pisces. At 2 p.m. on the 

 afternoon of the 27th he is in conjiuiction with the Moon, 

 31^ to the north of her, and the same evening at 9 p.m. he 

 is in conjunction with the 6th magnitude star 73 Piscium, 

 Jupiter being lOJ south. The following phenomena of 

 the satellites occur while Jupiter is more than 8' above 

 and the Sun S'' below the horizon. On the 1st an 

 occultation reappearance of the third satellite at 5h. 45m. 

 P.M. ; an eclipse disappearance of the same satellite at 

 8h. 5m. 52s. p.m. ; and an eclipse reappearance at lOh. Im. 

 59s. P.M. On the 3i'd an occultation disappearance 

 of the first satellite at 9h. 54m. p.m. On the 4th a 

 transit ingress of the first satellite at 7h. 3m. p.m. ; of its 

 shadow at 8h. 12m. p.m. ; a transit egress of the first 

 satellite at 9h. 17m. p.m. ; an occultation disappearance 

 of the second satellite at lOh. 11m. p.m. ; and a 

 transit egress of the shadow of the first satellite at lOh. 

 26m. P.M. On the 5th an eclipse reappearance of the first 

 satellite at 7h. 41m. 49s. p.m. On the 6th a transit egress 

 of the shadow of the first satellite at 4h. 55m. p.m. ; a transit 

 ingress of the second satellite at 5h. 8m. p.m. ; a transit 

 ingress of its shadow at 7h. 80m. p.m. ; a transit egress of 

 the satellite at 7h. 41m. p.m., and of its shadow at 9h. 58m. 

 p.m. On the 8th an occultation disappearance of the third 

 satellite at 7h. 5m. p.m., and its reappearance from 

 occultation at 9h. 27m. p.m. On the 10th an occultation 

 disappearance of the first satellite at llh. 44m. p.m. On 

 the 11th a transit ingress of the first satellite at 8h. 54m. 

 P.M. ; a transit ingress of its shadow at lOh. 8m. p.m., and a 

 transit egress of the satelUte one hour later. On the 12th 

 an occultation disappearance of the first satellite at 6h. 12m. 

 p.m., and its reappearance from echpse at 9h. 37m. 39s. 

 P.M. On the 13th a transit egress of the first satellite at 

 5h. 86m. P.M. ; of its shadow at 6h. 50m. p.m. ; a transit 

 ingress of the second satellite at 7h. 37m. p.m. ; of its 

 shadow at lOh. 7m. p.m. ; and a transit egress of the 

 satellite itself three minutes later. On the 15th an eclipse 



