THE SOLAR SYSTEM.
This displays the whole Copernican or Solar System, with every planet and satellite in diurnal and annual motion! With awe and deference I offer this daring but humble transcript of creation! Enough, if one idea can be added, to the ingenuous mind, of the attributes and perfections of the Deity.
The Sun, a huge globe of fire (957,942 miles diameter, and consequently a million times as large as our Earth, and intended to give light, heat, and vegetation, to seven primary and at least eighteen secondary worlds) is placed in the centre of the system; and by spots on his disk is discovered to turn on his axis in about 25 of our days. These spots cannot be permanently fixed, because they are frequently altering in their shape, situation, number, &c. tho’ some have supposed they have seen small indentations on the edge of the Sun, as the spots have passed it, and conjectured that a fluid matter surrounded a dark nucleus, which sometimes becoming bare, might occasion the transient appearance and disappearance of the spots.
Mercury is the first planet in the order of the system; about 3498 miles diameter: he moves round the Sun with the greatest velocity of any of the Planets familiar to our system (as being nearest the Sun) in about 88 of our days; at the rate of 110,680 English miles every hour, but the angle of his distance from the Sun, as seen by us, is so small, that unless by the telescope, we can seldom discern him[2]; (and even then an equatorial instrument to direct to its place, as indicated by the Ephemeris, will be requisite;) and when we do, it is for so short a time, and in twilight, that we can discover no spots on his face, and therefore to this hour know nothing of the length of his days and nights: we see him partially enlightened like the Moon, sometimes like a small crescent, in other situations half enlightened, and sometimes gibbous or oval, and are therefore certain he derives his light from the Sun, as she does: so that no doubt he is a fellow world, with inhabitants adapted to the heat of his situation: altho’ this heat is seven times as great as that of the Earth. He is not much larger than the Moon. Our Earth, viewed from Mercury, must appear much larger and more luminous than any of the Planets, except Venus, appears to us.
Venus is the next planet in the order of the system, and distinguished by her superior brilliancy, as the Sun’s light is twice as great to this planet as to the Earth; from this cause she is sometimes visible to the naked eye in full day-light. She is about 70 millions of miles from the Sun, or about twice the distance of Mercury; and like him, but much longer and more conspicuously, appears under the different phases of the Moon. These, as we have said, are proofs that both planets borrow their light from the Sun. The orbits of these planets (as well as those of the rest of the system) are inclined to the orbit of the Earth. Hence when Venus and Mercury are found in the nodes of their orbits between the Earth and Sun, they are transferred upon the Sun’s face like small round black spots, and which in fact are partial Eclipses of the Sun; these are called the transits of Mercury, or Venus.
Venus is a little larger than the Earth, or 9360 miles diameter; and moves round the Sun in 224½ of our days, at the rate of 80,955 miles every hour. From faint spots seen upon her surface, Mr. Shroeter apprehends she revolves on her axis in 23 hours, 21 minutes; that her surface is irregular like that of the Moon, and some of her mountains four miles high. The atmosphere of Venus has been calculated to be 50 miles high: and the Sun would appear to the inhabitants of this planet twice as large as to us. When Venus is to the west of the Sun, she is a morning star; when to the east of him, an evening star: her orbit or track is included by the Earth’s, and as both move the same way, she appears to be on one side of the Sun longer than the 224½ days she is in going round him. The axis of Venus is said by some astronomers to incline 75 degrees to the axis of her orbit: and therefore her seasons vary very fast, the Sun passing over more of her from pole to pole in one day, than over the Earth in a quarter of a year. Hence the heated places of this planet have time to cool: which suggest to our ideas that provision has been made for inhabitants, that they might not suffer by their vicinity to the Sun; this circumstance also gives her two winters and two summers at her equator, and indicates her inhabited. The discovery lately made by Mr. Shroeter, of a light faintly extended beyond the bounds of direct solar illumination, when she has her falcated appearance like the Moon near to her change, strengthens this probability: as these are signs of twilight, and of an atmosphere. This astronomer has also observed her to have considerable mountains; another character of a globe suited for habitation.
The Earth is the third planet in the order of the system: 8244 miles diameter—moves at the rate of 68,856 miles every hour, and hence completes its revolution in its orbit (the Ecliptic) in 365 days and ¼. The Moon’s diameter is 2183 miles; she moves with respect to the Earth 2290 miles in her orbit every hour; and goes round the Earth from change to change in 29 days and a half. But having devoted so much of this tract to the phænomena of the Earth, as well as its satellite the Moon, we proceed to
Mars, known in the heavens by his peculiarly red appearance, arising from a very thick and dense atmosphere. This Planet is next above the Earth, and hence has considerable less light from the Sun than we have; is much smaller than the Earth, or about 4470 miles diameter. He is near 150 millions of miles from the Sun, and goes round him in something less than two of our years, moving at the rate of 55,783 miles every hour. His day and night is rather longer than ours, or 24h. 39m. 22s. and uniform throughout his year, so that his axis being perpendicular, he has no variety of seasons. When we pass between the Sun and him he has a most fiery and alarming appearance, and is often mistaken for a Comet; but when we are on the opposite side of our orbit, he appears small, and scarcely to be distinguished from a fixed star.
Jupiter, far the largest of our Planets, near 1300 times the size of the Earth, or 93,333 miles diameter, is the next above Mars, at five times the distance from the Sun that we are; so that he enjoys but a twenty-fifth part of the light, heat, and attraction of that luminary we do.—Though indeed of the light and heat he may still possess, we are not so certain as of the degree of attraction: that being invariably proportioned to the distance; while these will be relative to the density and other circumstances of the atmosphere, and the aptness of the surface of the Planet to acquire and retain heat: after Venus he appears the most brilliant Planet of the Universe. He is attended with four satellites that revolve very regularly round him. The three first are eclipsed every revolution, and every seventh day come in conjunction with him and one another, as may be seen on the Eidouranion. Longitude, at land, can be ascertained by the eclipses of Jupiter’s satellites, as well as by a transit of Venus; and these would supercede the necessity of a time-keeper, if they could be observed at sea; hence, in the Nautical Almanack, these eclipses are very exactly calculated for the meridian of Greenwich, and answer very good geographical as well as nautical purposes. Jupiter is near twelve years in making his way round the Sun, altho’ he moves at the rate of 30,193 miles every hour; he turns round his axis in about ten of our hours, so that his days and nights are but five hours each: and he has no variety of seasons; for his axis is perpendicular to the plane of his orbit. Turning so swiftly on his axis, his figure becomes more oblate than that of the Earth, being more than 6000 miles longer in diameter from one side of his equator to the other, than from pole to pole, or in the proportion of 13 to 14.[3] This swiftness of his diurnal motion also draws his clouds and vapours into streaks or lines over his equatorial parts, forming what are called Jupiter’s Belts. An eclipse of the Sun, by this great planet, would be a striking object even to the unassisted sight as viewed from Saturn.