ROUGH ASTRONOMICAL NOTES

Evening Star, Issue 3932, 1 October 1875, Page 2

ROUGH ASTRONOMICAL NOTES

OCTOBER, 1875. 1. The Sun is now lOmin 6;ecs, and nt the end of the month he will be in advance of a chick showing mean time. But fow spots were visible during the last mouth, and those that were seen by us were very small. The days are lengthening rapidly, as the Sun is moving south at the rate of nearly a degree in three days. 2 The Moon will be in apogee on the sth at about 9 a.m., and in perigee on the 17th, at about 7 a.m. The phases will take place as follows : First Quarter on the Pth, at 3hrs 35miu a.m. Full Moon on the 15th at lOhrs ■Minin a.m. Last Quarter on tho 22ud at Ihr 43miu a.m. Now Moon on the 29th at 4hrs 43mm p.m. 3. Meicmy will bo very favorably situated for observation_ during tho first half of the month. He will be at his greatest elongation (25° 16' E.) on the 7tb; he will also be nearly 12° S. of the San. On that day, or probably two or three days later, he will present the appearance of a beautiful little half-moon, his apparent diameter being very nearly seven seconds. This diameter will gradually increase, and the phase as gradually decrease, till the planet reaches its inferior con* junction with the Sun on the Soi.h of the month. Mercury will be in conjunction with Jupiter on the sth but considerably (3° 56') S, • with Venus on the 2(ith; and with Jupiter again on the 27th. It is almost unnecessaiy to say that, unhss the weather ia very fiue, his telescope good, though not necessarily large, and his eye accustomed to making astronomic*! observations, the amateur has but little chance of _ getting a s:ti;'-f-ctory view of Mercury. Still anyone who really wishes to make Ids acquaintance would do w. 11 to make the most of the present opportunity, as so favorable an elongation seldom oceans. '.I he naked-eyo will easily find Mercury, lie is the bright “star” nearest to Jupiter. It wili he noticed that while Jupiter remains quite steady, Mercury twinkles with great rapidity. du the 7til he will set about 2hrs li'min ufier the Sun. ■l. Venus is now an “ evening but as ihe sets a few minutes after the Sun, she is, of course, quite invisible to the naked eye. 5. Aims is moving to the cast. Ho ia gibbous, very much so indeed, seeing that ho will bo iu quadratuio with the Sun on tho 24th, After that time his disc will begin to “ fill out” again. Wars is rapidly becoming fainter, and at the same time redder. He is east of the second trapezium of Sagittarius. 6. Jupiter is visible in the twilight, but long before the end of |}ie month he will have left us for the season. 7. Saturn is somewhat to the west of his last month’s position ; he will be stationary on the 2nh, at which time his rings will 1e in abetter position than they will occupy for many a year io come. After the date meniioued Saturn will resuue bis eastward maich among the Kf.VS.

8 Uranus is a morning star. i». Neptune will be in opposition on the 25th; he now rises at about a quarter past eight in ■ he evening. He has just entered the constellation Aries. He is not near any conspicuous star, is very badly situated, and is likely to be so for some time to come. Those of our readers who have the patience to wait some sixty years or so may • xpeet to find his position begin to imi ro\ e a bttle. The iutw ost attached to this planet is of a purely scientific character. In a

three-inch telescope he appears as a dull, illdefined, greenish, Bmag. star. Iu an B£-ineh reflector he is but little improved. He is not worth looking nt; that is the fact. hut as some of our readers might probably like to see him, we shall give a method by which ho may certainly be found. This method is p sufficiently troublesome one, but no other that we know of would answer the purpose while the planet is so far away from any star of moderate size. On the 25th of the month, at about half-jmt eight o’clock in the evening, find the star Zeta Pega&i, and bring it no.ir tho bottom of the held of view, a power of about 70 being used ; leave tho telescope undisturbed for 3hrs 25m iu 1 theca, when IN cptuno will be found very near the centre of the field of view'. If the experiment should he tried a day or two before the date mentioned, it will be necessai3 T to lengthen the time of waiting at the rate of six seconds per day ; if a day or two after, tho time must he shortened to the same extent. When once he has been found, it will not be difficult to pick him up again, us his configuration with the neighboring small stars may be noticed and made of use after wards. JN.B.—If a day-glass be used, the star must be placed at the top of tho field. Zeta Pegasi is the second large star south {receding hlarkflb—the upper left-hand star of the square of Pegasus.