THE FACE OF THE SKY FOR APRIL 



By A. C. D. CROMMELIN, B.A., D.Sc, F.R.A.S. 



Table 18. 



Table 19. 



P is the position angle of the North end of the body's axis measured eastward from the North Point of the disc. B, L 

 are the helio-(planeto-)graphical latitude and longitude of the centre of the disc. In the case of Jupiter L t refers to the 

 equatorial zone, L. 2 to the temperate zone, T,, T. 2 are the times of passage of the two zero meridians across the centre of the 



disc ; to find intermediate passages apply multiples of 9 5O2 1 



respectively. 



The letters in, e, stand for morning, evening. The day is taken as beginning at midnight. 



The Sun continues his Northward march. Sunrise during 

 April changes from 5-38 to 4-37; sunset from 6-31 to 7-19. 

 Its semi-diameter diminishes from 16' 2" to 15' 54". A small 

 partial eclipse of the Sun on the 6th, is visible in Alaska and 

 surrounding regions. 



Mercury is a morning star, well-placed for Southern 

 observers. Illumination one-thirtieth on 1st, one-half on 30th. 

 Semi-diameter diminishes from 5i" to 3i". Greatest Elonga- 

 tion, 27° West on 25th. 



Venus is an evening Star, till, the 24th, when it is in 

 inferior conjunction with the Sun, 6° North of it. Its semi- 



diameter is then 29i". It is of interest to see how near 

 conjunction it can be followed. Sometimes the unillumined 

 disc appears darker than the surrounding sky. Venus is 

 4° N. of Moon on evening of 8th. 



The Moon.— New 6 d 5 h 48 m e; First Quarter 14 d 5 h 39 m w; 

 Full 20 d 9" 31™e; Last Quarter 28 d 6 h 9 m m. Apogee 

 2 d 8 h e, semi-diameter 14' 45"; Perigee 18 d 5 h e, semi-diameter 

 16' 29". Apogee 30 d l h e, semi-diameter 14' 47". Maximum 

 Librations, ll d 6° E, 12 d 7° S., 24 d 6° W., 25 d T N. The 

 letters indicate the region of the Moon's limb brought into 

 view by libration. E. VV. are with reference to our sky, not as 

 they would appear to an observer on the Moon. 



Table 20. Occultations of stars by the Moon visible at Greenwich. 



From New to Full disappearances take place at the Dark Limb, from Full to New reappearances. 



112 



