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James. You told us a few days ago, that the sun has a rotation on its axis; how is that known?

Tutor. By the spots on his surface it is known that he completes a revolution from west to east on his axis in about 25 days, two days less than his apparent revolution, in consequence of the earth's motion in her orbit, in the same direction.

Charles. Is the figure of the sun globular?

Tutor. No; the motion about its axis renders it spheroidical, having its diameter at the equator longer than that which passes through the poles.

The sun's diameter is more than equal to 100 diameters of the earth, and therefore his bulk must be more than a million of times greater than that of the earth; but the density of

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the matter of which it is composed is four times less than the density of our globe.

We have already seen that, by the attraction of the sun, the planets are retained in their orbits, and that to him they are indebted for light, heat, and motion:

Fairest of Beings! first created light:

Prime cause of beauty! for from thee alone
The sparkling gem, the vegetable race,

The nobler worlds that live and breathe their

charms,

The lovely hues peculiar to each tribe,

From thy unfailing source of splendour draw!
In thy pure shine, with transport I survey
This firmament, and these her rolling worlds,
Their magnitudes and motions.—

MALLET'S EXCURSION.

We can hardly suppose, however, that the sun, a body three hundred times larger than all the planets together, was created only to preserve

the periodic motions, and give light and heat to the planets. Many astronomers have conjectured that its atmosphere only is luminous, while its body is opaque and probably of a constitution analogous to that of the planets. Allowing, therefore, that its luminous atmosphere only extricates heat, we see no reason why the sun itself should not be inhabited.

James. For my part, sir, I am at once inclined to believe this; because it accords completely with all one's preconceived sentiments of the wisdom and goodness of the Great Creator of the universe.

CONVERSATION XXVI.

Of the Fixed Stars.

TUTOR.

We will now put an end

to our astronomical Conversations, by referring again to the fixed stars, which, like our sun, shine by their own light, or that of their phosphorescent atmospheres.

Charles. Is it then certain that the fixed stars are of themselves luminous bodies; and that the planets borrow their light from the sun?

Tutor. By the help of telescopes it is known that Mercury, Venus, and Mars, shine by a borrowed light, for, like the moon, they are observed to have different phases according as they are differently situated with re

gard to the sun. The immense distances of Jupiter, Saturn, and the Herschel planet, do not allow the difference between the perfect and imperfect illumination of their disks or phases to be perceptible,

Now the distance of the fixed stars from the earth is so great, that reflected light would be much too weak ever to reach the eye of an observer here. James. Is this distance ascertained with any degree of precision?

Tutor. It is not: but it is known with certainty to be so great, that the whole diameter of the earth's orbit, viz. 190 millions of miles, is but a point in comparison of it; and hence it is inferred, that the distance of the nearest fixed star cannot be less than a hundred thousand times the length of the earth's orbit; that is, a hundred thousand times 190 millions of

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