The Night Sky in January

Abstract

THE moon is full on January 13 at llh. and new on January 27 at llh. U.T. No star as bright as mag. 5·0 is occulted during the month. Jupiter and Saturn are in conjunction with the moon on January 7 at 7h. and 12h. respectively; Mars is in conjunction on January 23 and Venus on January 25. Jupiter and Saturn are near the southern meridian in the early evening. Saturn is stationary in its movement among the stars on January 10, after which the planet increases its right ascension very slowly. Jupiter's right ascension is increasing appreciably, thus bringing the two planets more closely together in the sky until the middle of February (conjunction on February 20 at 19h.). Jupiter's four inner satellites may be seen grouped most closely together, at 20½h. on January 1, 4 (all eastwards), 11, 17 (all westwards), 19, 25 and 28. They will be seen widely grouped on January 8, 9, 13 and 31 (all westwards). Saturn's ring system is well presented for observation. Mars and Venus are both morning stars, the former predominantly bright in the morning skies before dawn. Clear evenings in January and February are associated with the brilliant assembly of stars attendant upon Orion. The Milky Way in this part of the sky is much fainter and less interesting than along its stretch visible during autumn evenings. During January, the night—sunset to sunrise—shortens by 1.2 hours in the latitude of London.