Caroline. The square of ten is a hundred; therefore, Saturn has a hundred times less—or to answer your question exactly, we have a hundred times more light and heat, than Saturn—this certainly does not increase my wish to become one of the poor wretches who inhabit that planet.
Mrs. B. May not the inhabitants of Mercury, with equal plausibility, pity us for the insupportable coldness of our situation; and those of Jupiter and Saturn for our intolerable heat? The Almighty power which created these planets, and placed them in their several orbits, has no doubt peopled them with beings, whose bodies are adapted to the various temperatures and elements, in which they are situated. If we judge from the analogy of our own earth, or from that of the great and universal beneficence of Providence, we must conclude this to be the case.
Caroline. Are not comets, in some respects similar to planets?
Mrs. B. Yes, they are; for by the reappearance of some of them, at stated times, they are known to revolve round the sun; but in orbits so extremely eccentric, that they disappear for a great number of years. If they are inhabited, it must be by a species of beings very different, not only from the inhabitants of this, but from those of any of the other planets, as they must experience the greatest vicissitudes of heat and cold; one part of their orbit being so near the sun, that their heat, when there, is computed to be greater than that of red-hot iron; in this part of its orbit, the comet emits a luminous vapour, called the tail, which it gradually loses as it recedes from the sun; and the comet itself totally disappears from our sight, in the more distant parts of its orbit, which extends considerably beyond that of the furthest planet.
The number of comets belonging to our system cannot be ascertained, as some of them are several centuries before they make their reappearance. The number that are known by their regular reappearance is, I believe, only three, although their whole number is very considerable.
Emily. Pray, Mrs. B., what are the constellations?
Mrs. B. They are the fixed stars; which the ancients, in order to recognise them, formed into groups, and gave the names of the figures, which you find delineated on the celestial globe. In order to show their proper situations in the heavens, they should be painted on the internal surface of a hollow sphere, from the centre of which you should view them; you would then behold them as they appear to be situated in the heavens. The twelve constellations, called the signs of the zodiac, are those which are so situated, that the earth, in its annual revolution, passes directly between them, and the sun. Their names are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricornus, Aquarius, Pisces; the whole occupying a complete circle, or broad belt, in the heavens, called the zodiac. ([plate 8. fig. 1.]) Hence, a right line drawn from the earth, and passing through the sun, would reach one of these constellations, and the sun is said to be in that constellation at which the line terminates: thus, when the earth is at A, the sun would appear to be in the constellation or sign Aries; when the earth is at B, the sun would appear in Cancer; when the earth was at C, the sun would be in Libra; and when the earth was at D, the sun would be in Capricorn. You are aware that it is the real motion of the earth in its orbit, which gives to the sun this apparent motion through the signs. This circle, in which the sun thus appears to move, and which passes through the middle of the zodiac, is called the ecliptic.
Caroline. But many of the stars in these constellations appear beyond the zodiac.
