Abstract
ON December 22 the sun enters the sign Capricornus (the winter solstice). The night reckoned from sunset to sunrise then lasts 16¼ hours in the latitude of London. Full moon is on December 14 and new moon on December 28. At meridian passage soon after 0h. on December 15 at Greenwich, the moon's altitude is 57°. Jupiter and Saturn, the conspicuous pair of bright planets, are visible throughout the greater part of the night. On December 11, they are in conjunction with the moon at 1h. and 6h. respectively. (All times are given in Universal Time; add 1h. to convert into Summer Time.) Mars is a morning star rising about half an hour before Venus on December 15. These two planets are in conjunction with one another on December 2 at 12h. On December 25 at 18h., Mars is in conjunction with the moon, and Venus is likewise in conjunction on December 26 at 18h. The rapidly changing positions of Jupiter's four inner satellites, their transits and eclipses, may be followed from the data given on p. 630 of the Nautical Almanac or on p. 182 of Whitaker's Almanack. Saturn's unique ring system is well open; a refractor of 2 inches aperture or larger is, however, required to resolve the rings. The bright stars of Perseus, Auriga, Taurus and Orion (with Procyon and Sirius in train), bring glory to the December night skies. There are the open star clusters of Perseus, the Pleiades and the Hyades: many well-known double stars, variable stars and nebulæ in abundance. Near φ Tauri is a dark nebulous region which Barnard considered as giving the strongest proof of the existence of obscuring matter in space. Near the irregular variable star, T Tauri, is the remarkable object known as Hind's variable nebula. Two notable nebulæ, exemplifying two distinct types, are both visible to the naked eye on moonless nights during this month. These are the great nebulæ of Orion and Andromeda—the first a greatly extended diffuse nebula of radiating gas lying within our Milky Way system: the second, a vastly remote stellar system in itself, the prototype of many millions which are shown on long-exposure plates taken with the largest reflecting telescopes. At midnight on December 31-January 1, 1941, Sirius, the brightest star in the heavens, is within 2 minutes of the southern meridian of Greenwich.
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The Night Sky in December. Nature 146, 715 (1940). https://doi.org/10.1038/146715b0
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DOI: https://doi.org/10.1038/146715b0