ASTRONOMICAL NOTES FOR SEPTEMBER.

Wairarapa Age, Volume XXXII, Issue 9585, 3 September 1909, Page 3

ASTRONOMICAL NOTES FOR SEPTEMBER.

!.By S. btuart, British Association). In addition to Venus, the little planet Mercury will be seen in our western evening sky this month, as he now ceases his movement on the western side of the sun, and moves to the east. He passes his aphelion, or most distant point from the sun in space, on the Bth, between five and six p.m. and, passing onward in his orbit, the moon catches up with him on the 17th, at about six a.m., when he will be situated about eight degrees to the south of her. By the 17th he will be most favourably situated for observers with or without telescopes, since between eight and nine p.m. on that evening he will be found at his greateat angular distance from the sun towards the east. 2G degrees 34 minutes, and will not set until about eight p.m. At this time he will be seen as a twinkling reddish-yellow star, of nearly the first magnitude, some 20 degrees to the &outh-west of Venus, or lower down in the sky; observers are not likely to mistake him for a fixed star, although he twinkles like one. On the 29th, between three and four a.m., he ceases his forward motion in the ecliptic, and for the moment becomes etationary, before turning retrograde or moving backwards. For the present this little planet moves between the first and 28 degrees of the sign Libra, in the first to the fourth degrees of south altitude.

I The brilliant Venus remains queen of the west where she shines with increasing brilliancy, and is most conspicuous of all the stars, and as her distance to the south nf the ecliptic increases she is setting latter each evening; on the 15th at Bh. 44m. p.m. She has most rapidly increased her distance from Jupiter since her very near approach to him on the 12th of last month, which, j fortunately, was well seen, and was : a very striking phenomenon. Un the 11th Verus will be exactly in the ecliptic at noon, or in no latitude; and on the 18th, near eight a.m. will be near the moon, and some four degrees to the south of her centreOn the 17th, nearly at noon, she leaves the sign Libra, and enters that of Scorpio, her present course being from the 11th degree of Libra to the 16th of Scorpio, in the first and second degrees of latitude south of the elliptic. Mars appears to have been the subject of much trepidation to some people, who took his red light in the east and near the horizon , for that of an airship. This probably arose from his alternate bright and more obscure shining, as the vapours near the horizon cleared away or partially hid him. But he is a sufficient object of interest without the somewhat appropriate scare of invasion thus given to him. He will this month reach his greatest brilliancy; but previously to this he will be seen on the evening ol the 2nd very near to the moon as she rises, and about three degrees to the sou|;h-east of her centime. On the 15th he will rise at 6hr 36 min p.m., and on the 24th at 9hr. 20min. p.m.. will beexaciy in opposition to the sun, or separated by half the circle of the heavens from our central luminary. At this time Mars will be at his most brilliant illumination to u", and most favourably situated lor observers. Forty-two instances of this postion are .given by Tycho Brahe and other observers between the years 1580 and 1610. including positions near it, and from which they computed its exact date, for it was most impottant to them as being the point at which the place the stars, as it appears from the sun, was the same as we see it from the earth: and Kepler was indebted to these observations for his immortal discovery of the true form ot the orbit of Mars and of all the planets. On the 29th Mars will again be seen very near the moon on rising. The planet Saturn is nov\ c itiveniently situated for seeing, as-iti the 15th hj? rises at 8.6 p.m. On -.he 3rd he will be occulated or eclij s ii by the moon, but beneath our horizon, which observeres need the less regret as the same phenomenon returns again on the 30th, near midnight, of which full particulars will then be published. Saturn is but a dull and pale looking star compared with Jupiter and Venus, but much more interesting than the latter for the telescopist, on account of hia rings.

On the 7th, at 7.14 a.m., the moon is in her last quarter, and on the 15th, at 3.39 a.rr.., is new moon, the sun and moon being then situated in lha 22nd degree of the sign Virgo. Anyone who will take the trouble to watch how the longitude of the new moon work 3 forward with each .lunation, will see how the signs of the zodiac have probably orginated; for-thc movement is nearly 30 degrees, or one sign, for each lunar month. On tha 23rd, at 6.2. a.m. is the first quarter, and on the 29th, at 12.35 (which is the 30th at 35m. a.m.), will be full moon, when our satellite will be situated in the 6th degree of the sign Arie3. The moon pursues a very eccentric orbit around the earth, for which reason she is alternately at her greatest and least distanca from it, which points are called respectively her apogee and perigree. In the present case she is in her apogee on thhe 16th, at. nine p.m., and in her perigree on the 30th at 4 30 a.m. Speaking of the signs of the zodiac, observers who may be on the lookout on the 15th, at nine p.m., will see the striking constellation Scorpio about half way up between the meridian and the south-western horizon, its bright star Antares on the scorpion's heart, conspicuous in the middle of it, and easily recognised by its red colour. In the south-east-ern sky, at about the same altitude, will be seen the brililant Star Fomalhaut, and a line drawn thence through Achernar, in a south-by-east direction, will light upon Canopu, just emerging the extreme southern horizon. These stars are the principal ones in their constellations, and it has always been an object of much interest to astronomers to determine at what epoch these groupings originated. Dupois supposed the 12 signs of the zodiacal band to have beer formed 15,000 years ago, when they rose with the sun in the corresponding months; but, as that date was considered inadmissable, Laplace supposed them to have been formed by the Egyp-

tians when the respective constellations rose opposite to the sun, about 2,700 years ago. One very striking argument that they are not of older date than the historic period is that there is no constellations of ancient formation in the heavens beyond what are visible from latitude 38 uegrees north, i.e., from Southern Egypt. In other words, there were no constellations formed in the skies beyond that region of them visible to the ancient world known'to Us,