days and nights, and the different seasons in this planet, will bear a considerable resemblance to those we experience in our terrestrial sphere.*

At his nearest approach to the earth, his distance from us is about 50 millions of miles; and, at his greatest distance, he is about 240 millions of miles; so that in the former case he appears nearly 25 times larger than in the latter. To a spectator in this planet, our earth will appear, alternately, as a morning and evening star, and will exhibit all the phases of the moon, just as Venus does to us, but with a less degree of apparent magnitude and splendour. A luminous zone has been observed about the poles of Mars, which is subject to successive changes. Dr. Herschel supposes that it is produced by the reflection of the sun's light from his frozen regions, and that the melting of these masses of polar ice is the cause of the variation in its magnitude and appearance. This planet moves, in its orbit, at the rate of fifty-five thousand miles an hour.

The new planets.-Between the orbits of Mars and Jupiter, four planetary bodies have been lately discovered, accompanied with circumstances somewhat different from those of the other bodies which compose our system. They are named Ceres, Pallas, Juno, and Vesta. The planet Ceres was discovered at Palermo, in Sicily, by M. Piazzi, on the first day of the present century. It is of a ruddy colour, and appears abour the size of a star of the 8th magnitude, and is consequently invisible to the naked eye. It performs its revolution in 4 years and 7 months, at the distance of 260 millions of miles from the sun, and is reckoned, by some astronomers, to be about 1624 miles in diameter, or about half the diameter of Mercury. It appears to be surrounded with a large dense atmosphere. -Pallas was discovered the following year, namely, on the 28th of March, 1802, by Dr. Olbers of Bremen. It is supposed to be about 2000 miles in diameter, or nearly the size of the moon. It revolves about the sun in 4 years and 7 months, or nearly in the same time as Ceres, at the distance of 266 millions of miles; and is surrounded with a nebulosity or atmosphere, above 400 miles in height, similar to that of Ceres. The planet Juno was discovered on the 1st September, 1804, by Mr. Harding of Bremen. Its mean distance from the sun is about 253 millions of miles; its revolution is completed in 4 years and 130 days, and its diameter is computed to be about 1425 miles. It is free from the nebulosity which surrounds Pallas, and is distinguished from all the other planets by the

The inclination cf the earth's axis to the ecliptic, or, in other words, to the plane of its annual orbit, is 23 degrees and 28 minutes, which is the cause of the diversity of seasons, and of the different length of days and nights. Were the axis of the earth per

pendicular to its orbit, as is the case with the pla

net Jupiter, there would be no diversity of seasons.

great eccentricity of its orbit; being, at its least distance from the sun, only 189 millions of miles, and at its greatest distance 316 millions.-Vesta was discovered by Dr. Olbers on the 29th March, 1807. It appears like a star of the 5th or 6th magnitude, and may sometimes be distinguished by the naked eye. Its light is more intense and white than any of the other three, and it is not surrounded with any nebulosity. It is distant from the sun about 225 millions of miles, and completes its revolution in 3 years and 240 days. Its diameter has not yet been accurately ascertained; but from the intensity of its light, and other circumstances, it is concluded, that it exceeds in magnitude both Pallas and Juno.

These planetary globes present to our view a variety of anomalies and singularities, which appear incompatible with the regularity, proportion, and harmony which were formerly supposed to characterize the arrangements of the solar system. They are bodies much smaller in size than the other planets-they revolve nearly at the same distances from the sun, and perform their revolutions in nearly the same periodstheir orbits are much more eccentric, and have a much greater degree of inclination to the ecliptic, than those of the old planets-and, what is altogether singular, (except in case of comets,) their orbits cross each other; so that there is a possibility that two of these bodies might happen to interfere, and to strike each other, in the course of their revolutions. The orbit of Ceres crosses the orbit of Pallas. Vesta may sometimes be at a greater distance from the sun than either Ceres, Pallas or Juno, although its mean distance is less than that of either of them, by several millions of miles; so that the orbit of Vesta crosses the orbits of all the other three. From these and other circumstances, it has, with a high degree of probability, been concluded-that these four planets are the fragments of a large celestial body which once revolved between Mars and Jupiter, and which had been burst asunder by some immense irruptive force. This idea seems to have occurred to Dr. Olbers after he had discovered the planet Pallas, and he imagined that other fragments might possibly exist. He concluded, that, if they all diverged from the same point, "they ought to have two common points of reunion, or two nodes in opposite regions of the heavens, through which all the planetary fragments must sooner or later "" pass. One of these nodes he found to be in the constellation Virgo, and the other in the Whale; and it is a remarkable coincidence, that it was in the latter of these regions that the planet Juno was discovered by Mr. Harding. In order to detect the remaining fragments (if any existed) Dr. Olbers examined, three times every year, all the small stars in Virgo and the Whale; and it was actually in the consellation Virgo, that he dis covered the planet Vesta. It is not unlikely.

that other fragments of a similar description may be discovered. Dr. Brewster attributes the fall of meteoric stones* to the smaller fragments of these bodies happening to come within the sphere of the earth's attraction. His ingenious reasonings on this subject, and in support of Dr. Olbers' hypothesis above stated, may be seen in Edin. Ency. vol. ii. p. 641, and in his "Supplementary chapters to Ferguson's Astronomy.'

The facts to which I have now adverted seem to unfold a new scene in the history of the dispensations of the Almighty, and to warrant the conclusion, that the earth is not the only globe in the universe which is subject to physical, changes and moral revolutions.

The Planet Jupiter.-This planet is 490 millions of miles distant from the sun, and performs its annual revolution in nearly twelve of our years, moving at the rate of twenty-nine thousand miles an hour. It is the largest planet in the solar system; being 89,000 miles in diameter, or about fourteen hundred times larger than the earth. Its motion round its axis is performed in nine hours and fifty-six minutes; and, therefore, the portions of its surface about the equator move at the rate of 28,000 miles an hour, which is nearly twenty-seven times swifter than the earth's diurnal rotation. The figure of Jupiter is that of an oblate spheroid, the axis, or diameter passing through the poles, being about 6000 miles shorter than that passing through the equator. The Earth, Saturn, and Mars are also spheroids; and it is highly probable that Mercury, Venus, and Herschel are of a similar figure, though the fact has not yet been ascertained by actual observation. When viewed with a telescope, several spots have been occasionally discovered on the surface of this planet, by the motion of which, its rotation was determined.

But what chiefly distinguishes the surface of Jupiter is several streaky appearances, or dusky strips, which extend across his disk, in lines parallel to his equator. These are generally

• Meteoric stones, or, what are generally termed aerolites, are stones which sometimes fall from the upper regions of the atmosphere, upon the earth.The substance of which they are composed is, for the most part, metallic; but the ore of which they consist is not to be found in the same constituent proportions in any terrestrial substances. Their fall is generally preceded by a luminous appearance, a hissing noise, and a loud explosion; and, when found immediately after their descent, are always hot.Their size differs, from small fragments, of inconsiderable weignt, to the most ponderous masses. Some of the largest portions of these stones have been found to weigh from 300 lbs. to several tons; and they have often descended to the earth with a force

sufficient to bury them many feet under the soil.Some have supposed that these bodies are projected from volcanoes in the moon; others, that they proceed from volcanoes on the earth; while others imagine that they are generated in the regions of the atmosphere; but the true cause is, probably, not yet ascertained. In some instances, these stones have penstrated through the roofs of houses, and proved destructive to the inhabitants.

zonsa

termed his belts. Three of these belts, or zoNOL
termed his belts.
nearly equi-distant from each other, are most fre›
quently observed; but they are not regular or
constant in their appearance.† Sometimes ly
one is to be seen, sometimes five, and sometimes
and,
seven or eight have been distinctly visible;
in the latter case, two of them have been known
to disappear during the time of observation. On
the 28th May, 1780, Dr. Herschel perceived
"the whole surface of Jupiter covered with small
curved belts, or rather lines, that were not con-
tinuous across his disk." Though these belts
are generally parallel to each other, yet they are
Their breadth is likewise varia-
not always so.
ble; one belt having been observed to grow nar-
row, while another in its neighbourhood has in-
creased in breadth, as if the one had flowed into
the other. The time of their continuance is also
uncertain; sometimes they remain unchanged
for several months, at other times, new belts
What
have been formed in an hour or two.
these belts or variable appearances are it is diffi-
cult to determine. Some have regarded them as
strata of clouds floating in the atmosphere of Ju-
piter; while others imagine, that they are the
marks of great physical revolutions which are
marks of great
perpetually changing the surface of that planet.
The former opinion appears the most probable.
But, whatever be the nature of these belts, the
sudden changes to which they are.occasionally
subject, seem to indicate the rapid operation of
some powerful physical agency; for some of
them are more than five thousand miles in
breadth; and since they have been known to dis-
appear in the space of an hour or two, and even
during the time of a casual observation-agents
more powerful than any with which we are ac-
quainted must have produced so extensive an
effect.

Jupiter is attended by four satellites or moons,
which present a very beautiful appearance when
viewed through a telescope. The first moon, or
that nearest the planet, is 230,000 miles distant
from its centre, and goes round it in 42 hours;
and will appear from its surface four times
The second
larger than our moon does to us.
moon, being farther distant, will appear about
the size of ours; the third, somewhat less; and
the fourth, which is a million of miles distant
from Jupiter, and takes sixteen days to go
him, will appear only about one-third the diame
ter of our moon. These moons suffer frequent
eclipses from passing through Jupiter's shadow,
in the same way as our moon is eclipsed by
passing through the shadow of the earth. By

round

↑ A representation of these belts, in the positions in which they most frequently appear, is exhibited in the engraving, Fig. 2. Fig. 1. represents the double ring of Saturn, as it appears when viewed through a powerful telescope-Figures 1, 2, 3, 4, and 5, represent Saturn, Jupiter, Herschel, the Earth and Moon, in their relative sizes and pro portions.

the eclipse of these moons, the motion of light was ascertained; and they are found to be of essential use in determining the longitude of places on the surface of our globe. This planet, if seen from its nearest moon, will present a surface a thousand times as large as our moon does to us, and will appear in the form of a crescent, a halfmoon, a gibbous phase, and a full-moon, in reguar succession, every 24 hours. Jupiter's axis being nearly perpendicular to his orbit, he has no sensible change of seasons, such as we experience on the earth. Were we placed on he surface of this planet, with the limited powers of vision we now possess, our earth and moon would entirely disappear, as if they were blotted out from the map of creation; and the inhabitants of these regions must have much better eyes than ours, if they know that there is such a globe as the earth in the universe.

The planet Saturn.-This planet is 900 millions of miles distant from the sun, being nearly double the distance of Jupiter. Its diameter is 79,000 miles, and, consequently, it is more than nine hundred times the bulk of the earth. It takes 291⁄2 years to complete its revolution about the sun; but its diurnal motion is completed in ten hours and sixteen minutes; so that the year in this planet is nearly thirty times the length of ours, while the day is shorter, by more than onehalf. The year, therefore, contains about twenty-five thousand one hundred and fifty days, or periods of its diurnal rotation, which is equal to 10,759 of our days. Saturn is of a spheroidal figure, or somewhat of the shape of an orange; his equatorial being more than six thousand miles longer than his polar diameter. His surface, like that of Jupiter, is diversified with belts and dark spots. Dr. Herschel, at certain times, perceived five belts on his surface, three of which were dark, and two bright. The dark belts had a yellowish tinge, and generally covered a larger zone of the disk of Saturn, than the belts of Jupiter occupy upon his surface. On account of the great distance of this planet from the sun, the light it receives from that luminary is only the ninetieth purt of what we enjoy; but, by calcula tion, it is found, that this quantity is a thousand times greater than the light which the full moon affords to us. Besides, it is surrounded by no fewer than seven moons, which supply it with light in the absence of the sun. Five of these moons were discovered during the seventeenth century, by Huygens and Cassini; and the sixth and seventh were discovered by Dr. Herschel, in 1789, soon after his large forty feet reflecting telescope was constructed. These moons, and These moons. and also those which accompany Jupiter, are estimated to be not less than the earth in magnitude, and are found, like our moon, to revolve round their axis in the same time in which they revolve about their respective primaries.

circumstance connected with this planet, is, the phenomenon of a double ring, which surrounds its body, but no where touches it, being thirty thousand miles distant from any part of the planet, and is carried along with the planet in its circuit round the sun. This is the most singular and astonishing object in the whole range of the planetary system; no other planet being found environed with so wonderful an appendage; and the planets which may belong to other systems, being placed beyond the reach of our observations, no idea can be formed of the peculiar apparatus with which any of them may be furnished. This double ring consists of two concentric rings, detached from each other; the innermost of which is nearly three times as broad as the outermost. The outside diameter of the exterior ring is 204,000 miles; and, consequently, its circumference will measure six hundred and forty thousand miles, or eighty times the diameter of our globe. Its breadth is 7,200 miles, or nearly the diameter of the earth. Were four hundred and fifty globes, of the size of the earth, placed close to one another, on a plane, this immense ring would enclose the whole of them, together with all the interstices, or open spaces between the different globes. The outside diameter of the innermost ring is 184,000 miles, and its breadth twenty thousand miles, or about 2} times broader than the diameter of the earth. The dark space, or interval, between the two rings, is 2,800 miles. The breadth of both the rings, including the dark space between them, is thirty thousand miles, which is equal to the distance of the innermost ring from the body of Saturn.

The following figure represents a view of Saturn and his rings, as they would appear, wero our eye perpendicular to one of the planes of those rings; but our eye is never so much elevated above either plane, as to have the visual ray standing at right angles to it; it is never elevated more than 30 degrees above the planes of the rings. When we view Saturn through a telescope, we always see the ring at an oblique angle, so that it appears of an oval form, the outward circular rim being projected into an ellipsis more or less oblong, according to the different degrees of obliquity with which it is viewed, as will be seen in the figure of Saturn in the copperplate engraving.

These rings cast a deep shadow upon the planet, which proves that they are not shining fluids, but composed of solid matter. They appear to be possessed of a higher reflective power than the surface of Saturn; as the light reflected by them is more brilliant than that of the planet. One obvious use of this double ring is. to reflect light upon the planet, in the absence of the sun; what other purposes it may be intended to subserve, in the system of Saturn, is, Rings of Saturn. The most extraordinary at present, to us unknown. The sun illuminates