THE star-maps published every month in the Scientific American represent the sky as it appears to an observer in the latitude of New York (approximately 40 degrees north) and consequently fail to show the stars within 40 degrees of the south celestial pole, which are visible only in lower latitudes. To meet the needs of observers in the southern part of the United States, or in more southern countries, the accompanying map has been prepared, showing all the stars clearly visible to the naked eye, within 60 degrees of the south pole. The whole region of the heavens here represented can be seen at once only from points in extreme southern latitudes. From stations north of the equator, less than half of it is visible at any one time. It is, however, very easy to adjust the map so as to show just what southern stars are in sight from any given station, at any day and hour. We need only know the observer's latitude (which can be obtained with sufficient accuracy from any good atlas) and the sidereal time. The latter can be found closely enough for our purpose by adding together three numbers: 1 the local time as given by an ordinary clock; 2, the quantity given in the accompanying table for the current month; 3, four minutes for each day of the month to date. h. m, January ..........18 39 February ......... 20 41 March . .-......... 22 32 April ............. 0 34 May.............. 2 32 June ............. 4 34 July .............. 6 31 August ........... 8 35 September........ 10 37 October .......... 12 35 November ........ 14 38 December ........ 16 30 Midnight should be counted as 12 hours, 1 A. as 13 hours, and so on, and, if the sum exceeds 24 hours, this amount should be subtracted from it. For example, for 1 :15 A. M. on October 25th, we have: h. m, Clock time ....... 13 15 From table, for October .......... 12 35 4 X 25 = 100 minutes, or......... 1 40 Sum ......... 27 30 Subtract 24 hours. 24 0 Sidereal time ..... 3 30 The results of this calculation will be correct within four or five minutes at the most, if the observer's clock keeps local time. If it keeps standard time, the result should be corrected by the amount by which standard time is fast or slow of local time. For our present purpose, this correction is usually hardly necessary. Find now the point on the margin of the map corresponding to the sidereal time, by means of the scale of hours and minutes on the edge, and turn the map till this point is at the top. Then lay a straight edge across it so that it passes above the center, at a distance equal to the observer's latitude (if north of the equator). As the white circles on the map are 10 degrees, 20 degrees, 30 degrees, etc., from the center, this can be done very easily. The part of the map above the straight edge then represents the southern sky, as it appears above the observer's horizon. In strict accuracy, the line representing the horizon should be curved, so as to be about one-third nearer the horizontal diameter of the map at the edges than at the center; but this too is of small practical importance. For stations south of the equator, where the south celestial pole is above the horizon, the straight edge should be held below the center of the map, at a distance equal to the latitude.. Stars in other parts of the sky than the south may lie identified by the aid of the maps published every month. The present map is purposely made to overlap the southern” portions of these by about twenty degrees, to facilitate passing from one to the other. The familiar aspect of the northern heavens on a winter evening needs little description. Orion and Canis Major blaze in the south, with Argo on the horizon below them. Gemini and Canis Minor are east and southeast of the zenith, Auriga directly overhead, and Taurus southwest of him. The planets Mars and Saturn, near together, between Taurus and Aries, increase the brightness of what “is at all times the most brilliant region of the starry sphere. Hydra, Leo, and Ursa Major are conspicuous in the eastern skies; Draco, Ursa Minor, and Cassiopeia in the north, and Perseus and Andromeda in the north- west. The only really dull region is in the southwest, which is filled rather than illumined by Pisces, Cetus, and Eridanus. The Planets. Mercury is morning star all through January. He is best seen about the 15th, when he is nearly 24 degrees from the sun. Being far south of the equator, in Sagittarius, he rises relatively late, about 5 :45 A. M. ; but he can be readily seen, before dawn, appearing as a star about as bright as Vega. Venus is likewise morning star, in Scorpio, rising about 4 :30 A. M. in the middle of the month. Jupiter is a morning star, too, in the same region of the sky. On the 9th the two planets are in conjunction. Venus, which is about 1% degrees north of Jupiter, appears about eight times as bright to the eye as he does, but in the telescope shows a disk little more than half as big. This very great difference in the apparent brightness of the surfaces of the two planets does not arise from differences in their reflecting power, but from the fact that Venus being relatively near the sun receives about fifty times the strength of sunlight that Jupiter does. Mars is in Taurus, not very far from the Pleiades, and comes to the meridian at 8 P. M. in the middle of the month. He is rapidly receding from the earth, being 65,000,000 miles away on the 1st, and 88,000,000 on the 31st, and in consequence he diminishes steadily in brightness. At the beginning of the year he is twice as bright as Arcturus, and excelled only by Sirius, but at its end he is hardly equal to Capella. Saturn is in Aries, about 10 degrees west of Mars, and appears about as bright as Procyon. His distance from the earth is so great—over 800,000,000 miles— that the forty millions by which it increases during the month makes but a small percentage of change ill his apparent size and brightness. Uranus is in conjunction with the sun on the 20th, and is invisible throughout the month. Neptune is in opposition on the 13th, and is well observable throughout the month. His exact position may be found at any time by interpolation between the two places: h.rn. s. deg. m. Dec. 31.. 7 37 58 + 20 57.2 Feb. 1.. 7 34 13 + 21 6.2 This puts him very near the line drawn from 5 Ge-minorum to a point found by carrying a line from fJ Geminorum through k, and as far again. He appears as a star of magnitude 7.6, and can only be seen with telescopic aid. The Moon is full at 7 A. M. on the 4th, in her last quarter at 2 A. M. on the llth, new at 5 A. M. on the 19th, and in • her first quarter at 3 A. M. on the 27 th. She is nearest us on the 4th, and farthest a way on the 17th. As the full Moon comes almost exactly at the time of perigee, we may expect unusually high—and low—tides on and about the 4th. The Moon is in conjunction with Mars on the morning of New Year's Day. and an occultation is visible, in the morning hours, from points in the southwestern portion of the United States. She is also _in conjunction with Neptune on the 4th, Jupiter and Venus on the 15th, Mercury on the 17th, Uranus on the 19th, Saturn on the 27th, and Mars again on the 28th, when a second occultation may be seen in the extreme north of this country. A comet, visible in a small telescope, was discovered by the French as-.ronomer Schaumasse on November 30th. It is moving slowly eastward through the northern part of Virgo, and increasing in brightness. On January 1st it will be in about 15 hours 15 minutes R. A. and 2 degrees south declination, moving about 1 degree east and 15 minutes south per day. The first calculation of its orbit (by the discoverer and an associate) shows that it is still approaching the sun, and will not reach perihelion till February 5th, at which date it will be 108 million miles from the sun, and rather more distant from the earth. It will never be very near us, and in consequence may not be at all conspicuous; but it will be observable in the morning sky for some three months to come. Princeton University Observatory. Largest University in the World REGISTRATION, now complete at Columbia University, shows that the attendance upon the university courses for the scholastic year is 7,468 as compared with 6,842 last year, an increase of 626, and, including the extension courses, the number is only eight short of 8,000. This places Columbia at the head of all other universities in the world in point of attendance, taking the place of Berlin, which stood at the head last year.
This article was originally published with the title "The Heavens in January"