The Solar System consists of the Sun, of seven Planets surrounded by ten or more Moons, and of the Comets. The other siderial lights with which the vault of Heaven is studded, and which are denominated Fixed Stars, have a very distant affinity with our planetary sphere: they are infinitely too remote to be enlightened by our luminary; and therefore astronomers, with good reason, imagine each star to be a sun to encircling planets, though invisible to us; and to constitute throughout boundless space thousands, or perhaps millions, of habitable worlds. Numbers of those stars, most luminous and proximate, are arranged into arbitrary clusters, called Constellations, or Signs; and serve to mark the several stages of the rotating orbs in our system.
The Sun, whose magnitude far surpasses that of the seven planets united, is placed in the center, suspended in the immense celestial expansion and firmament. Surrounding him, at different distances, and in the following order, are the planets Mercury, Venus, the Earth, Mars, Jupiter, Saturn, Georgium Sidus. These planets are incessantly revolving from west-by-south to east, and within certain intervals of time, make a complete circle round the Sun; which is the length of each planet’s year; and is larger and longer in proportion to their respective distances. The velocity of their revolution in their annual orbits, together with their gradations of light and heat, are also in proportion to their solar proximity. From the Sun, the Planets, with their surrounding moons, derive heat and light; and when this is intercepted by any planet, or its satellite, an eclipse or darkness ensues. In what periods those tremendous celestial bodies, named Comets, revolve round the Sun, is not yet exactly adjusted.
One of the seven planets, the Earth, this small domain of restless mortals, and to which all our future observations shall be directed, is distant from the Sun 95,173,000 miles. In shape, it has more resemblance to a turnip than to a globe. Its diameter is 7,970 miles: its circumference 360 degrees; which amounts to 24,840 English miles. Geographers divide the globe of our planet into two equal parts, or hemispheres, the northern and southern, by an imaginary girdle, or ring, named the Equator. Two other imaginary girdles surrounding the earth, and distant from the equator on each side 23½ degrees, north and south latitude, are named the Tropicks of Cancer and Capricorn; comprehending between them the torrid zone. From these tropical circles the zones, called Temperate, extend on each side 43 degrees: and at their extreme boundaries, we reach the polar circles 23½ degrees distant from each pole. The north and the south poles are in the middle of each hemisphere of the earth; and the distance of each from the equator is 90 degrees.