and a star between them. The character of Ceres is a sickle, or reaping-hook ; and Pallas is represented by the head of an ancient spear'-Prior's Lectures. VESTA. Vesta, though the nearest of the Asteroids to the Sun, was the last discovered, being first seen by Dr. Olbers, of Bremen, in Lower Saxony, on the 29th of March, 1807. It may be seen in a clear evening by the naked eye. Its light is more white, pure, and intense than that of the other Asteroids. It is not surrounded by nebulosity and has no visible disk.) Mean diameter of Vesta, 238 miles. Mean distance from the Sun, 225,000,000 miles. Tropical revolution, 3 y. 60 d. 4 h. Place of the aphelion, in 1809, 2 s. 9° 42′ 53′′. JUNO. Juno, or Harding, was discovered by Mr. Harding) of Lilienthal, near Bremen September 1st, 1804) Appearing like a star of the eighth magnitude, it is of a reddish color free from the nebulosity observable in Pallas. Yet it may be concluded from Mr. Schroeter's observations, that (it must have an atmosphere more dense than any of the primary planets, except the Asteroids. A remarkable variation in the brilliancy of Juno was observed by this astronomer. He attributed this to the changes taking place in the atmosphere. He thinks, however, these changes may arise from a diurnal rotation in 27 hours. The most singular circumstance respecting Juno, is the great eccentricity of its orbit as may be seen by inspection of the elements. Mean diameter of Juno, 1,425 miles. Tropical revolution, 4 y. 128 d. Place of aphelion in 1809, 7 s. 29° 49′ 33′′. CERES. The discovery of Ceres, as we have seen, led the van of discoveries in the present century. It was made by Piazzi, astronomer royal at Palermo, on the first day of January, 1801.) According to some, it is about the size of the Moon, appearing like a star of the eighth magnitude. Dr. Herschel's measurement, however, made its diameter 13 times less than that of the Moon. The planet Ceres is of a ruddy color, though not very deeply tinged, Examined by a magnifying power of about 200, it exhibits a disk surrounded by a dense and extended atmosphere. By many observations, Mr. Schroeter found this atmosphere (subject to various changes, and extended to the great height of 675 miles. But little opportunity is given for discovering the diurnal rotation of this planet, the visible hemisphere being interchangeable, overshadowed, and clear. The atmosphere of Ceres, like that of the Earth, very dense at the planet, and more rare at a distance, produces singular variations in its apparent diameter.”) The disk seems to enlarge when the planet is approaching the Earth, much faster than might be expected from the diminution of distance. Mean diameter of Ceres, 163 miles. Do. according to Schroeter, 1,624 miles. Mean distance from the Sun, 263,000,000 miles. Tropical revolution, 4 y. 220 d. 12 h. 53 m. 34 s. Longitude of ascending node, 2 s. 21° 6′ 0′′. PALLAS. Pallas, discovered by Dr. Olbers, on the 26th of March, 1802 is in magnitude nearly the same as Ceres, but of a color less ruddy. It is surrounded with nebulosity, similar in appearance to that of Ceres, and extended to a height almost equal. In the eccentricity of its orbit, it resembles Juno. Pallas is distinguished from all the other primary planets by the great inclination of its orbit to the plane of the ecliptic, being about 35°; nearly five times the inclination of Mercury's orbit. Mean diameter of Pallas, according to Herschel, 80 miles. Do. according to Schroeter, 2,099 miles. Mean distance from the Sun, 265,000,000 miles. Tropical revolution, 4 y. 7 m. 11 d. Place of aphelion in 1802, 10 s. 1° 7′ 0′′. The mean distances of these Asteroids from the Sun being comparatively equal, but the inclination of their orbits, and the position of the line of their apsides, different, their orbits intersect each other. (Plate i. Fig. 3.) Whether they will ever come in conflict is uncertain, but may be determined by future observations and the calculation of succeeding astronomers. We know they are guided by infinite wisdom. Much labor and ingenuity have been employed to show, that these Asteroids are but fragments of a larger planet burst asunder by some vast explosion. The hypothesis seems not supported by conclusive arguments. Against it there are strong reasons. The idea itself of such an explosion seems extravagant beyond conception. How vast must have been the force which could throw such bodies from each other to a distance of 40 millions of miles; or so as to revolve in orbits 40 millions of miles distant! Immense is the explosive force of Hecla, throwing lava or cinders to the distance of 150 miles. But how diminutive! How are all the explosions of Vesuvius and Hecla, of Etna and Cotopaxi, annihilated in comparison! Had these Asteroids constituted but one planet, since the first attention to the heavenly bodies, it would have been seen by ancient astronomers, being sufficiently large for observation by the naked eye. It would have been enumerated among the planets. It may be added that the vast atmosphere of some of these planets, which would, without doubt, have been left behind in such an explosion, seems directly opposed to the idea of their having been hurled from a bursting planet. Of what is the term Asteroid compounded? What are the Asteroids? What caused some astronomers to suppose there was a planet between Mars and Jupiter? On what day was the first of the Asteroids discovered? By what characters are the Asteroids represented? When and by whom was Vesta discovered? How does its light differ from that of the other Asteroids? Has it nebulosity or a disk? Who discovered Juno? When? What are the apparent magnitude and color of Juno? Has it an atmosphere? What is the most singular circumstance respecting Juno? What led the van of discoveries in the present century? When was Ceres discovered? By whom? What is the color of Ceres? What kind of atmosphere has this planet? What produces singular variations in its apparent diameter ? What are those variations? Who discovered Pallas ? At what time? How are its magnitude and color? Has it nebulosity or an atmosphere? In what is it distinguished from all the primary planets? What is remarkable in the orbits of the Asteroids? What have much labor and ingenuity been employed to show? What objections can be offered to the hypothesis that the Asteroids formerly constituted but one planet? SECTION XI. Of Jupiter. Beyond the Asteroids, or farther distant from the Sun, is Jupiter, the largest of the planets. Jupiter, next to Venus, is the most brilliant of the planets.) He sometimes even surpasses her in brightness. The form of Jupiter is an oblate spheroid,) his equatorial diameter being to his polar, as 14 to 13. The character 2, by which this planet is represented by astronomers, is a zeta, the first letter of his Greek name, Zeus; the lower part cut off by a small line drawn across, as a sign of abbreviation. The most remarkable phenomena in the disk of Jupiter is a number of belts or stripes, by which he is encompassed. These appear variable at different times, and even at the same time, viewed by telescopes of different powers. Yet they generally appear parallel to each other, and parallel to the equator of Jupiter. In very favorable weather, they sometimes seem formed of a number of curved lines, like the strokes of an engraving. Eight or ten belts have been seen at the same time. The belts have been observed, at times, of different breadths, and have afterwards all assumed nearly the same breadth. (Bright and dark spots)are frequently visible in these belts. Like the belts, the spots are subject to continual change. When a belt vanishes, the contiguous spots disappear. Some of the spots, however, seem to make periodical returns.) The spot first observed by Cassini re-appeared eight times between the years 1665 and 1708. In 1713, it again re-appeared, in the same form and position. In 1780, May 28, the disk of Jupiter was observed by Dr. Herschel, covered with small, curved belts, or rather lines not contiguous, as in Plate iii, Fig. 7 and 8. Parallel belts, however, as represented in Plate iii, Fig. 9, are most common. Different opinions are formed by astronomers respecting the cause of these appearances. By some they are considered the effect of changes in the atmosphere surrounding Jupiter, while they are regarded by others as indications of great physical revolutions on the surface of the planet. By others, again, it is supposed that the |