BOUGH ASTRONOMICAL NOTES

Evening Star, Issue 3569, 31 July 1874, Page 2

BOUGH ASTRONOMICAL NOTES

Fob the use of Star.gazebs.

August, 1874.

1. The Sun is just now very free from spots : those that do appear on its disc are, for the most part, very small. 2. The Moon will be in Perigee on the Ist, and in Apogee on the 17th of the month. Last quarter on the 4th, at lOhrs. 9min. a.m. Now -Moon on the 12th, at 3hrs. 22min, p.m. First quarter on the 20th, at 6hrs. 15min. p. m. Full Moon on the 28th, at 12hrs. 50min. a.m.

3. Mercury will be very badly situated for observation during the whole of this month. It will be at its greatest W. elongation, only 18 deg. 43min., on the 14th. Besides being low down, it will be about 4deg. N. of the Sun; consequently it will be even then very difficult to catch sight of it. It may be looked for an tour before sunrise, N. of the Sun’s track. 4. Venus still continues to be the most striking object in the sky. In the telescope it somewhat resembles the Moon as seen by the naked eye, when it is about nine days old, ex«ept that it is very much brighter and has no markings on its surface. This planet will bo -quite close to the star Beta Virginis at about 11 p.m. on the 7th. It will also be near Jupiter on the evenings of the 12th aud 13th. At this time a comparison may be made of the relative brightness of the two planets; but as Jupiter will before long be at its greatest distance from the Earth, it will not appear to advantage. The apparent diameter of Venus is beginning to increase very rapidly; before the «nd of the month it will subtend an arc of 18iec.

5. Mars is practically invisible. 6. Jupiter cannot be mistaken. Though much excelled by Venus, it is still a fine object. Its lower dark belt (in the astronomical telescope) is unusually well marked just pow. Throughout the month Venus and Jupiter will make the north-west quarter of the evening sky very interesting to astromaniacs. 7. Saturn will be in opposition to the Sun on the 4th; its apparent diameter is 18min. 12sec, It will rise on that date at about a quarter to five in the evening, somewhat to the south of east. Saturn is considered by many to be the finest of telescopic objects. Sir G-. Airey and Mr Proctor both attribute to their first view of this planet their enthusiasm for the science of astronomy. 8. Uranus and Neptune cannot be seen— Uranus, because it is in conjunction with the Sun, and Neptune, because it is (as always) too far from the Earth. 9. The Comet,—Early last evening this visitor was, owing to the absence of the moon, pretty well seen. It was about 2deg. south, preceding a third magnitude star in Arge Navis, just on the border of that .constellation. Owing to our unfavorable situation, the low altitude of the comet, and the strong twilight, we could not make out whether the star was Xi or Bho Argfts. At all events, the comet is proceeding south very rapidly indeed. It is probable that it may continue visible for jsome time. It is daily becoming better situated for observation in the evening, and its apparent size is not diminishing very rapidly, so that it may yet be possible to get a good telescopic view of it. The best instrument for viewing it is a good field glass: in a telescope with power 25 a pretty clearly defined nucleus was plainly to be seen,

but the eomet’s tail was almost invisible. The field-glass shows a fine coma, and a tail of about 3deg. in length. The tail is, as usual, turned away from the sun. It will be visible this evening just after sunset, low down in the southwestern sky. Its motion is direct, that is from west to east, rather than from east to west. Its orbit is inclined to the ecliptic, at an angle of about 70deg.

POSITIONS OP FIRST MAGNITUDE STAftS. August Ist, 1874, at about 11 p.ro. August 15th, „ „ 10 p.m. Looking North.—At a moderate elevation nearly due north is Altair, or Alpha of the Eagle. This star is in a line with and between two other moderately bright stars, "Very low down, a little to the left of north, is Vega, a very bright, bluish star, in the Harp. Looking West.—At a considerable elevation, there is a fine reddish star; this is Antares in the Scorpion. Spica in tire Virgin is just setting.

Looking East.—Foraalhaut is pretty high up, almost due east, in a region nearly bare of large stars. Looking South. Canopus is almost due south, very low down. To the left and much higher is Achernar. The Southern Cross, with its fine stars Alpha and Beta, is rather low down to the right. Above the Cross are Alpha and Beta Centauri; the latter being the lower of the two.