442 



KNOWLEDGE & SCIENTIFIC NEWS. 



[May, 1906. 



The Face of the Sky for May. 



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

 The Su.n". — On the ist the Sun rises at 4.35 and sets at 

 7.20; on the 31st he rises at 3.52 and sets at 8.3. 



Sunspots and facula^ are, at this period of solar activity, 

 usually to be seen on the Sun's disc. Several large sun- 

 spots have of late been observable on the disc at the 

 same time ; prominences also have been conspicuous on 

 the Sun's limb, as shown by spectroscopic observations. 



The position of the Sun's axis, equator, and helio- 

 graphic longitude of the centre of the disc is shown in 

 the following table : — 



The Moon : 



Date. 



Phases. 



H. M. 



May 



5 First Quarter 



O Full Moon 



S Last Quarter 



• New Moon 



■ First ( )uar;er 



7 7 p.m. 



2 10 p.m. 



7 3 a.m. 



5 I a.m. 



6 24 a.m. 



Perigee 

 Apogee 



6 p.m. 

 6 p.m. 



OccuLTATioNS. — There are no naked eye stars 

 occulted before midnight during this month ; on the 

 morning of the 6th at 1.33 a.m., however, there will be 

 an interesting occultation of the double star 7 \'irgini?. 



The Planets. — Mercury (May 1, R.A. o'^ S5" ; 

 Dec. N. 2° 47'. May 31, R..'\. 3I' 48"^ ; Dec. N. i9'~2o') 

 is a morning star in Pisces and Aries. The planet is at 

 greatest western elongation of 26 ' 46 on the 3rd, when 

 he rises about 4 a.m., or 33 minutes in advance of the 

 Sun, hence the elongation is not a favourable one. 



Venus (May i, K.A. 3'' 48""; Dec. N. 20° 16'. 

 May 31, R..^, 6^ 25""; Dec. N. 24° 45') is an evening 

 star in Taurus, setting about 9.45 p.m. on the 15th. 

 The planet appears very bright in the N.W. portion of 

 Ihe evening sky bad may be ob;er\ed thortly after sun- 

 set ; the disc is slightly gibbous and has an apparent 

 diameter of 11". On the evenings of the nth and 12th 

 the planet will be found in apparent proximity to Jupiter. 



Mars (May i, R.A. 3'! 59"> ; Dec. N. 21° 5'. May 31, 

 R.A. 5'' 27"'; Dec. N, 24"' o') is an evening star in 

 Taurus, setting about 9.20 p.m. throughout the month. 

 The planet may be observed shortly after sunset looking 

 to the north-west, but he does not appear very bright, and 

 is not suited for observation in small telescopes as his 

 apparent diameter is only 3"-8. On the evei ing of the 

 18th he appears in the sky about i^ north of Jupit:r. 



Jupiter (May i, R.A.4''32"> ; Dec. N. 21'^ 28'; May 31 

 R.A. 5h !"> ; Dec. N. 22° 22') is only available for obser- 

 vation for a short time after sunset, and after this month 

 will not again be observable as an evening star until Sep- 

 tember. The planet appears in too bright a part of the 

 sky for the satellites to be easily observed. 



During the early part of May the three most conspicu- 

 ous planets will appear close together and near the ist 

 magnitude star Aldebaran (a Tauri), which, though not a 

 matter of real astronomical interest, forms a rather un- 



usual appearance in the evening sky. The diagram shows 

 the positions on May 11, when the planets are all near 

 together, \'enus being the brightest and about 1° to the 

 north of Jupiter whilst Mars is feebly visible about 3'-' away. 



21, and Mars (?, 



The planets set about half past nine, and the moon, 

 which is full on the Stb, will be rising in the east. 



Saturn (May i, R.A. 22'' 58"' ; Dec. S. 8° 23'. May 31, 

 R.A. 23'' 6"^ ; Dec. S. 7 ' 45') is a morning star, rising 

 about 2 a.m. near the middle of the month. The planet 

 is situated in Aquarius. 



Uranus (May 15, R.A. 18';' 35'"; Dec. S. 23° 31') 

 rises about 11 p.m. near the middle of the month. The 

 planet is badly placed for observation, as he is situated 

 low down in Saggittarius. 



Neptune (May 15, R.A. 6i> 37'"; Dec. N. 22° 17') is 

 observable in the north-west portion of the evening sky 

 during the early part of the month; on the 15th the 

 planet sets about 11 p.m. 



Meteor Showers : — 



The principal shower during May is the Aquarids. 

 This may be looked for between May i to 6 ; the radiant 

 being in R.A. 22'' 32" Dec. S. 2°, near the star ,, Aquarii. 



Telescopic Orjects: — 



Double Stars. — Librae, XIV. *" 46", S. 15° 39', mags. 

 3, 6 ; separation 230" ; very wide pair. 



a Corona", XVI.h ii", N. 34' 8', mags. 6, 6i ; separa- 

 tion 4"-6 ; binary. 



a Herculis, XVII.'' id", N. 14° 30', mags. 2i, 6 ; 

 separation 4"-6. Very pretty double, with good contrast 

 of colours, the brighter component being orange, the 

 other blue. 



5 Herculis XML" ii", N. 24^ 57', mags. 3, 8 ; separa- 

 tion 17". 



Clusters. — M13 (cluster in Hercules) situated about 

 I the distance from •,, to j- Herculis, and is just visible to 

 the naked eye. It is a globular cluster, and with a 3 or 

 4 inch telescope the outlying parts of the cluster can be 

 resolved into a conglomeration of stars. 



