ROUGH ASTRONOMICAL NOTES.

Evening Star, Issue 4160, 27 June 1876, Page 3

ROUGH ASTRONOMICAL NOTES.

July, 1876.

1. The Sun will be at bis greatest distance from the earth on the Ist, at about 8 p.m. One small ■pot was visible on. the 25th. We saw none during the previous part of the month. 2. The moon will be in apogee on the 6th at about 11 a.m., and is perigee on the 20th at abont mid* sight.? The phases will take place as follows: Fuyhnoon, July 7th, at 3hrs Bmin a.in. ' last quarter, July 15th, at Ihr 25min a.m. New moon, Jaly 21st, at4hra 23min p.m.

First quarter,. July 28th, at 2hrs 49min, p.m.

The moon will be pretty close to Jupiter on the 2nd of the month, very close indeed to Antarea at about 2 o'clock on the morning of the 4th, near Saturn on the 11th, and near Jupiter Again on the 30th.

3. Mercury will be at his greatest elongation W. —-20deg 49min—on the 9th of the, month. At that time it should be possible to get avery fair view of the planet. He should ho looked for about half ahhour before sunrise; .a little to the S, of the sun's track, and in the most northern part of the con* stellation Ouon. .

4. Venus is new rapidlyretrograding and moving in towards the Sun. On the Ist'ofthe mouth she will pass the meridian only Ihr 25mihafter the Sun. There will be doily a rapid increase of even this short interval, and on the 14th, at 9 p.m., Venus will be in inferior conjunction with .the Sun. At her last inferior conjunction Venus was in a part of he t orbit that is, so to speak, on the same level with the Earth and the' Sun, and, as everybody knows, a transit of the planet took place. ' At the coming conjunction, however, Venus will be, if we may use the words, above the Sun; she will, in fact, ipass some Meg to the south ol him. Venus is now a beautiful object in the day-time, an ’ time spent ip “ Ashing her up " is well spent. She now looks like a young moon, and, unlike other ladies, she daily becomes younger. Her color may behest described as an intense silvery white. If proper precautions be taken to keep off the Snn’sglareit maybe possible to see her shortly before and very soon lifter hfer Inferior conjunction as an extremely slender curved thread of light. Possibly, too, she may present the appearance which we sometimes see in the case of the Moon—"the old moon in the new moon's arms.” After conjunction Venus will, of course, he a morning star. the end of the month she will be about as t £ar to the west of the Sun as she now is to the east. At the time of conjunction Venus will be very near the Earth. If we take the Earth's mean distance from the Sun ns 92,000,000 miles, Venus will be only some 26,700,000 mi es from the Earth, while her apparent semidiameter will be more than 57secs of arc. It may, perhaps, be worth mentioning that the inhabitants of Venus, if tbere are any, which is suAiciently doubtful, will have a splendid yfew of the Earth at the time of inferior conjunction. For them-the Earth will be in oppositi n’,'and will have on appearance somewhat similovito that presented to ns by Mors when he is most favorably situated fer observation; bat the Earth, with its smaller companion the Moon, will give a very.much greater amount of light to 'the Venus people than any planet, even Venus herself, ever does to us. It should be added, too, that the Moon will be well placed with regard to the Earth. She will not have, quite reached her greatest elon. gatibn from the Earth, but she will be far enough away to be comparatively clear of the glare of the larger planet. 5. Marais unfavorably situated for, observation; he is too far away from the Earth, arid almost put out by the Sun’s rays. 6. Jupiter is still in the constellation Libra. He will be stationary bn the 20th, and then will recommence his eastward march among the stars.' Jupiter is now favorably situated for observation as soon as the Son has set. Jupiter himself sets at about ten minutes post four in the morning. jitpiteb's satellites. [Ec., eclipse; 0., occultation; T., transit of satellite; S., transit of shadow: D., disappearance; 8., reappearancel., ingress; E., egress.J i

7. Satnrn rises-at about 9hrs 24miu p.m. Ha is still in the constellation Aquarius, and is now slowly retrograding. Satnrn will be in opposition next month.

8. Uranus will be., is conjunction with the Sun on the 13th. It is scarcely necessary to sajftthat it will he impossible to see him during this month. 9. Neptune requires no special mention this south. ■ ■. THE SOUTHEEN CONSTELLATIONS. V. The Toucak.—(Continued;. Outliers o{ the Nubecula Minor, or/Smaller Magellanic clouds, 1. 47 Toucani— B.A.. Ohrs 19min., Dec. 72° 46’S This is a unique und most splendid object. It precedes the Nubecula Minor, and is visible to the naked eye. It looks like a hazy fourth or fifth mag* nitude star. An opera-glass shows it as a luminous circle, very bright in the middle., and gradually fading away towards the circumference. This Magnificent globular cluster should be examined on a very fine night, so that a moderately- high power may be used; then the following particulars will be noticed. In the centre there is a bright “ blaze" nearly or quite circular in form and ol a reddish or orange tint; the component stars ar i here not separately discernible with a Herschel’s telescope of moderate size, but it is easy to see that the texture is “ velvety," to use an expression ofSir J. Herschel’e, and to believe that greater telescopic power would show the individual stars. Surrounding the blaze is a ring, very rich in s'ars, but easily resolvable; the outer diameter of this ring is five or six minutes of arc; outside of this is another ring, in which the stars are much more sparsely scattered than they are in the interior portions, but still very numerous. The outer diameter of this third ring is about eight minutes of ore. The cluster does not end here, however, for numerous stragglers con be seen all round the cluster. When once we have got beyond these stragglers we come upon a real region of “outer darkness," in which stars are indeed “ few and far between." To produce the appearances here described many thousands of stars must lend their aid. These are all of about the 12th and 13th magnitude, or nearly of the same size as those in the great cluster Omega Contauri, which, by-the-bye, is the only globular cluster that gKcela 47 Toucani in size. As far as symmetry and biaiity are concerned, the clnster that we are new - describing is without a peer j.eveh- the beautiful cluster In the northern constellation Hercules suffers by comparison with 47 Toucani. It is almost impossible to contemplate an object of this kind without asking oneself questions as to its comparative size and its distance from ns, Unfortunately, when we attempt to answer such questions, we find that we have no data to start from. If, however, wo might be allowed to adopt Mr Proctor’s view that the clusters and nebulae are not external “ MilSjrWays," but constituent parts of our owl, sidereal system ; and, if at the same we might assume that the distance frturns of the brightest globular clusters is not very different from the distance 1 of some of the brightest, fixed stars,, we ' Might' deduce a result that would probably aob’be outrageously wide of the motk;

There can be so harm in our doing this, if we re member that our results are founded on analogy and not on observed facts. If then we assume the distance of this globular cluster to be the suae aa that of Arqturus, the parallax of which is about oneeighth of a second of arc, we shall find the diameter of the globular cluster (Bmin. of arc) to bo equal to the continued product of the radius of the Barth's orbit (92,000,000 miles), by 480 and by 8, reckoning in the same way as we formerly did in the cose of Alpha Centauri. This continued product will be about one-third of a billion of miles. If we take the parallax of Sirius, which is about i quarter of a second, wo shall get a result equal to about one-half of this distance: that of the North Foie star, would give about double the distance. Wemay feel almost certain that these results do notorrin the way. of making the size of globular Clusters’ too small ; so that if this method of dealing with them does nothing else it showsus that they .must be -of enormous magnitude. The blue planetary nebula in the Southern ’Cross, if it is as distant as Aroturas, could take in within its bounds the whole of the solar system, with plenty of room to spare; but 47 Toncani would occupy in space a sphere, on a diameter of which more than sixty solar systems could be placed, side by side 1 Dunlop 62.—-B.A. Ohrs. 59$min. f Dec. 71° 29* S.

A fine globular cluster, bright and large; somewhat like 47 Toncani, but not nearly so large or bright,' It is situated at the N. foil, extremity of the Nqheoula. afoeimh

3F Note on the Spectrom of Beta Orals (i.e., the second Star of the Crane).~rlt. has been found that this star has a spectrum like that of Gamma Crnois, described in oar “ Notes" for March, that is to say, a very fine spectrom, fall of dark lines and bars.' 1 Circumstances will prevent the present writer from continuing .these papers; but no break will occur, as arrangements nave been made under which a gentleman having' every necessary qualiflcation. both aa ah astronomer and as a mathematician, will continue the Astronomical Notes. On one point only does the present writer feel some misgiving—it seems to him probable that the notes will not deserve in future to be called “ rough " to the same extent as they.sometimes have in the past.

| 2 .2 | & w a <g July — — 1.—Ec.E .? • ij ■ . 4 16 40 4.—T.I.J . 8 15 4.-S.I. ij . , 10 14 4.—T.E. ij . . 10 49 5.—T.I. j . . 11 14 6.—Ec E. i • 3 . . 7 915 6.—O.D, . 8 32 6.—£c.E. j • . 11 42 37 5.—T.I. ? • J . . 5 41 7.—S.I. . ■ 6 43 7.—T.E. j •• ; 7 54 7.—S.E, 1 . ,8 56 7.-O.D. iij - . 10 40 “8.—Ec.E, - ui . . 6 1116 11.—S.I. . 4 39 11. —S.E. iij . . 640 11.—T.I. j] • . 10 38 13.—O.D, il • , 458 13.—Ec.R, ij . . 946 34 13. —O.D. j . . 10 21 14,—T.I. 3 • j . . 7 31 14.—S.I. . 8 38 14.—T.E. 3 . .9 44 14.—S.E. 3 • . 10 51 15.—S.E. ij • ..4 42 15.—O.D. 3 • . 4 48 15.—Ec.E j ■ . 8 5 56 16.—S.E. j . . 5 20 18.—T.E. iij . ..6 1

ft*; 6 3 ■ .' July C{ 08 03 sip wal — 18.-S.L iij. . 839 19.—SB. lij . .10 40 20.-O.D. ij • . 7 26 21.—T.I. j . . 9 22 21.—S.I. j • . 10 S3 21.—T.E. i . . 11 35 22,—S.I. ii .. . .4 41 22.—T.E. ij . . 4 51 22.—O.D. r • . 6 89 22.—S.E. . . 7 17 22.—Ec.E j . .10 0 37 23.—S.I. j . . 5 2 23.—T.E. i . . 6 3 23.—S.E. J . . 7 15 25.—T.I. iij . . 7 42 25.—T.E, iij .. . 948 27.—O.D. Q • . 9 57 28.—T.I. j • . 11 15 29.—S.I, ij . . 7 15 29.—T.E. ij • . 7 20 29.—O.D. j . .8 81 29.-S.B. ij • . 9 52 29.—Ec.E j ■ . 11 55' 20 80.—T.I. j . . 5 43 SO,—SI. i. . 6 57 30.—T.E. j • . 7 56 30.—S.E. j. . 9 10 31.—Ec.E. j . . 6 24 1