Calm and serene in this dark vale of tears, Moon's Passage over the Meridian. P. From the passages of the Moon over the first meridian this month, the following have been selected as the most convenient for observation: viz. Sept. 8th, at 38 m. after 4 in the morning. 9th, 34 10th, 30 11th, 13th, 12 5 6 7 8 9 4 in the afternoon. 5 6 7 in the evening. 8 2 9 The phases of Venus were discovered by Galileo, in the year 1611; he sent the discovery to William de Medici, to communicate it to Kepler. It was conveyed in this cypher,-" Hæc immaturæ a me frustra leguntur, o, y;" which, properly arranged, is-" Cynthiæ figuras æmulatur mater amorum;" that is, "Venus emulates the phases of the moon." The comparative phases at the commencement of the present month are as follows: viz. Sept. 1st.-Illuminated part = 10.49884 Dark part......= 1.50116 Eclipses of the Satellites of Jupiter. The following are the visible eclipses of these satellites this month: viz. Conjunction of the Moon with the Fixed Stars. Sept. 5th, with › in Pisces at 10 at night. 7th, in Cetus.... 1 in the morn. Other Phenomena. Jupiter will be stationary on the 4th of this month. Venus and Saturn in conjunction at 6 in the morning of the 13th. Venus in conjunction with Regulus in Leo at 9 in the evening of the 14th. Mercury in conjunction with Spica Virginis on the 18th at midnight; at his greatest elongation on the 17th, and stationary on the 30th. MARS IN OPPOSITION. The planet Mars will be in this position of its orbit relative to the earth, at a quarter after 3 of the afternoon of the 19th of this month, near two small stars in Pisces. The situation of Mars, when in opposition, has long been of interest to the practical astronomer; next to a transit of Venus over the Sun's disc, it is the most eligible for determining the earth's distance from the Sun, though observations of the transits of the one, and the oppositions of the other, are methods not immediate and direct. A superior planet at the time of opposition is then nearest the earth, and its apparent place in the starry heavens coincides with its true place, or, the observed longitude is the same as the true longitude, all calculations being referred to the Sun as the centre; the nature of the observation is, to deterinine with good instruments, at places in opposite hemispheres, each about 50° or 60° from the equator, the positions of the planet, relative to the nearest fixed star, at the same moment of absolute time,— the difference of these positions will furnish sufficient data, to solve the interesting problem of planetary distances, which, in the case of Mars, indicates his horizontal parallax to be 23".6, and consequently his distance from the Sun 144 millions of miles. Mars is the only superior planet that exhibits a sensible deviation from a full disc; this occurs when he is in quadrature, and he then appears gibbous, being defective of his diameter; when Jupiter is similarly circumstanced, he is defective of his diameter; but this is a quantity too small to be detected by the most exquisite instruments. ΤΟ The diameter of Mars varies, (as with all the other planets,) according to his distance; the angle under which his disc is sometimes seen, when in opposition, is 56", its least, or when in conjunction with the Sun being 19"; when appearing under its greatest angle, it shines with a bright red light, and has been considered by many as a new star, for which it was taken in the year 1719. There seems some physical cause, (arising probably from his atmosphere, which is believed to be very dense,) that renders the surface of this planet occasionally so very indistinct; when in opposition, in 1828, the spots on his orb were remarkably distinct. There are several points of resemblance between Mars and our Earth; his daily motion, and the nature of his seasons are similar: the white spots observed about his poles are supposed to be masses of unmelted snows, in which a variation occurs, as either pole is turned towards the Sun by the planet's annual motion. METEOR. (Seen September 15th, 1829.) On the afternoon of Tuesday, the 15th instant, Deptford was visited by a short but violent storm of thunder and lightning: the flashes of lightning were of unusual vividness, and the peals of thunder very loud and protracted. At two minutes and a half after four a fire-ball fell a few yards to the north of St. Paul's church,-it was accompanied by a sharp cracking explosion; its course was from the west, and inclined to the horizon in an angle of about forty degrees; the more condensed part of the ball, as observed at the distance of about fifty yards, was probably nine or ten minutes in diameter, of an irregular form, and reddish hue; the color of the streams that proceeded from the upper part and sides more nearly resembled the flash of lightning with which the descent of the ball and the explosion was simultaneously attended. The storm came from the north-west, and did not continue longer than twenty minutes: about twelve minutes after the fire-ball fell, the Sun was shining clearly.— Literary Gazette. Halos accompanied with Colored Shadows. When in the neighbourhood of Candia, on the first of September, about sun-set, there was a large halo encircling the Sun, and to this succeeded a deep glow of evening crimson. The heavens were cloudless, and the sky was serene and clear. Under such circumstances as these, it was singular that every shadow in the ship was tinted: an occurrence which generally accompanies double refraction. The shadows which fell upon the white scuttles were of azure blue; and those that fell upon the rigging and sails, to which the Sun had imparted a slight reddish tint, varied from blue to green. The sea was agitated, and did not reflect the Sun. On those portions of the sails which the Sun had tinted with the deepest red, the green predominated over the blue. A similar, and no less brilliant appearance, was observed on the 3rd of September; and in both instances there was not only no double shadow, but the Sun was surrounded by a halo.The tint thus imparted to the shadows, must have arisen from the yellowish-grey stratum of mist, which lay between the ship and the Sun.Travels in Egypt, Libya, Nubia, and Dongola, between the Years 1820-1825. By Dr. C. G. Ehrenberg, and Dr. W. F. Hemprich. |