ASTRONOMICAL NOTES FOR FEBRUARY.

New Zealand Herald, Volume XLIV, Issue 13399, 30 January 1907, Page 4

ASTRONOMICAL NOTES FOR FEBRUARY.

BT 8. STUART, BRITISH ASTRONOMICAL ASSOCIATION'.

Tins month Mercury will again become visible as an evening star and above our western horizon, as lie will pass his superior conjunction with the sun on the 3rd between four and five a.m. In this position Mercury lias the sun between himself and the earth, and is at his greatest distance from us; but he thereafter gradually increases hi-" angular distance toward the east and so becomes visible to us. His greatest southern departure from the ecliptic towards the south as it would Ik- seen from the sun will occur on the 4th between ten and eleven a.m. After this we have to let some days elapse before there is much more to note until the 13th about the time of the planet's setting, when he will be situated about half a degree to the north of the moon, and this will be a favourable opportunity to find him if the sky should be anything like dark enough about the horizon; but it will probably be too light. However, it will serve to show how far the planet may be discoverable under such circumstances. On the 21st Mercury will be in conjunction with .Saturn, and ldeg. 40m. to the north of that planet, but it is very doubtful if the latter can be seen so near the sun as fourteen degree.-, from his disc. On the 22nd about noon Mercury will pass his ascending node and enter northern latitude from the ecliptic, and on the 28th, between one and two a.m., will be in his perihelion or nearest to the sun. This planet sets on the Ist at 7h. 14m.. and on the 15th at 6h. 29m. p.m.. thus keeping too near the sun for easy observation all tiie month, but his angular distance to the cast of that body on the 15th will be ten degrees, and on the 28th eighteen degrees. His course for the present will be from the 10th degree of Aquarius to the 26th degree of I'isces, and from the third degree of south latitude to the second degree of north. Venus remains a glorious object in our morning skies to the •eastward, as she will reach her greatest angular distance, to the west of the sun on the 9th between three and four p.m. On the 9th she will be situated a short distance to the east of the moon in the morning and will be in conjunction with our satellite about six in the evening, but this occurs below our horizon—a fact to be regretted, as it will be an occupation in this latitude to those more favourably situated. She will rise on the Ist at; 52m. after one a.m., and on the 15th at two minutes later; because, as she is so near her stationary point in the heavens as concerns the sun, her distance from him in the interval undergoes but a slight change, which her motion in declination tends to neutralise as far as our horizon is concerned. Her course during February will be from tin' 25th degree of Sagittarius to the 23rd degree of Capricorn, with latitude from four to two degrees north of the ecliptic. .Observers should be on the watch for Mars, as that planet will be the next evening star in our eastern sky, and rises on the Ist at llh. 34m.. and on the 15th at lib. 3m. p.m. An easy guide to his position will lie found on the 7th, when ho rises just before the moon and some four degrees to the south of her centre. This planet is remarkable for the long time which he remains invisible after disappearing in the sunrays, perhaps the longest of any of the planets; and this is the more notable, considering that he is such a very conspicuous object when we do see him. For the present he is moving between the 28th degree of Scorpio and the loth of Sagittarius, in the first degree of north latitude. Jupiter still remains the most conspicuous planet in the evening, as he passes the meridian on the Ist at 9h. 28m., and on the 15th at Bh. 30m. p.m., and is thus in a fine position for observing, though his distance from us is daily increasing, and therefore his visible diameter decreasing in proportion, together with the visibilty of his satellites. On the Bth, between noon and one p.m., ho will cross the ecliptic from south to north (which occurs but once in 12 years), and will thus bo found in north latitude for the next six years to come. On the 23rd. about six a.m., Jupiter and the moon will be in conjunction, but it is far below our horizon, with the planet some three degrees to the north of the moon. The retrogade motion of this planet will cease on the 26th, between eight and nine a.m., after which he' will resume his direct motion or towards the east. He is now moving from the 2nd to the Ist degree of the sign Cancer, retrograde; and from thence to the end of the month almost entirely stationary, the latitude within two minutes of the ecliptic. Those who may care to look for Saturn while he is so near the sun will have their best chance on the 14th alx>ut the time of setting, as the moon will then be a little to the cast of him, being in conjunction somewhere about an hour earlier, and a degree to the north of the moon's centre. If seen, the planet will be but a very dim star; but exact data as to when the planets respectively disappear as they approach the sun, and reappear when leaving him, are wanting ; moreover, it must be a variable quantity for each planet. Saturn- sets on the Ist at Bh. 49m., and on the 15th at 711. 57m. p.m., while his present movement is from the 14th to the 17th degree of thy sign Pisces, in the second degree of south latitude.

Uranus or Hersehell now rises on the Ist at 2h. 48m. a.m., and on the 15th at Hi, 58m., but as he is not near any conspicuous stars will not be easily found with the telescope. A guide to his position may lie found on the 10th, when he will be situated somewhat to the west of the moon, and two degrees to the south of her centre, but he is not in the neighbourhood of any conspicuous stars. His movements at present are confined to the 11th and 12th degrees of the sign Capricorn, in the Ist degree of south latitude.

Neptune, the most distant known planet of our system, will lx> on the meridian on the 18th at 101 i. 5m., and on the. 15th at 9h. 9ni., moving retrograde in the 11th and 10th degrees of the sign Cancer, and the first degree of south latitude. He will lie found near the moon on the 23rd, as the conjunction occurs about midnight.

In his annual visitation of the zodiacal signs, the sun will enter Pisces on the 20th at 6h. 28m. a.m., which is the last ingress he makes before reaching the equinox of autumn with us. At apparent noon by outdials or the sun on tho Ist, the. clocks in Auckland will show- 12h. 4in. 245., on the 15th 12h. sm. 135., and on the 28lh 12h. 3m. 375. The days are now rapidly shortening, and will soon cease to be as long as the nights; but it is noteworthy that, although the diurnal supply of sunlight is decreasing, the heat is if anything on the increase whenever the wind is otherwise than in tho .south: because the day is still longer than the night, and therefore the absorption of heat by the earth is still in advance of the amount radiated into space. The last quarter of the moon takes place on the 6th at 22m. past noon, and she is new on the 13th at 23m. after five a.m.. in the 23rd degree of Aquarius. On the 20th, at sm. after four p.m., will be the first. quarter, and on the 28th at sh. 53m. sh* will be full, in the Stli degree of the sign Virgo. She will lx? nearest, to the earth on the 10th at 6h. 36m. p.m., and most distant from us on the 22n<l at 24m. after noon. She will pass across the celestial equator from north to south on the 3rd at lib. 30m. p.m.. and in the opposite direction on the 16th at sh. 35m. p.m. In the intervals between these points she is at her greatest distance from the equator, as on the 10th, between nine and ten a.m.. when she will be in declination 21deg. 4m. south, and on the 24th, between three rind four a.m., in 21deg. 6m. north. As regards the ecliptic, she passes across it from north to .south on the 11th at sh. 55m. p.m., and from south to north on the 25th at sh. 57m. p.m. Her midway points will be tho.e of her greatest latitude from the ecliptic, such as the 4ili at. lib. 42m. a.in., when she is in sdeg. 15m. north latitude, and the 18th at 61i. 58m. a.m., in sJeg. 13m. south. On the 23rd, near midnight, she will Oetllt Neptune, though not visibly to us, and on the 9th Venus, as already described;