Part 2

§ 6. Besides the Planets and Moons there is yet another class of bodies, moving round the Sun in exceedingly long ovals. They are but seldom visible, and are distinguished from other heavenly bodies by a tail which is often three, four, and more times larger than the body itself. These are called Comets; but their number has not, as yet, been precisely ascertained.

§ 7. The Planets, Moons and Comets, together with the Sun around which they move, form what is called our Solar System. But what will you say, if you are told that each fixed Star in the firmament is a Sun which, like our’s, has its Planets and satellites and Comets; in short, that each fixed Star is the centre of a solar system, a thousand and more times larger than our own!! But how infinitely great must God’s Creation appear to us, when we reflect that all these globes, as well as our own, may be inhabited by reasonable beings!!!

RECAPITULATION OF LESSON I.

QUESTIONS.

What is the line in which our Earth moves round the Sun, called?

LESSON II.

OF THE PLANETS AND THEIR RELATIVE POSITION WITH REGARD TO THE SUN AND EACH OTHER.

§ 8. The Planets of which we have spoken in the First Lesson are Eleven in number, of which each has received a proper name. They are in the order in which they are placed from the Sun, the following:

Mercury. Venus. The Earth. Mars. Vesta. Juno. Ceres. Pallas. Jupiter. Saturn. Herschel.

The adjoining diagram, on Plate No. II, may serve for an illustration. You will see from it, that the Earth is the third Planet from the Sun. Mercury and Venus come before it; the most remote from the Sun is Herschel, so called from the astronomer’s name, who has but lately discovered it.

§ 9. The Earth is constantly attended by One Satellite (Lesson I, § 5); Jupiter by Four (see the diagram), Saturn by Six, and Herschel by Seven. Saturn is, besides, constantly surrounded by a broad luminous ring, which distinguishes it from all other Planets, and of which we shall speak hereafter.

§ 10. With regard to the magnitude of the different Planets it has been observed that although some of them are much larger than Our Earth; yet in Comparison to the Sun they are but small bodies, as you may see from the figures on plate No. III, in which the different Planets are drawn in proportion to the Sun: you will perceive from it;

1. That the Sun is a great many times larger than either of the Planets.

N^o. II. ]

N^o. III.. ]

2. That the Sun is much larger than all the Planets (our Earth included) taken together.

3. That Jupiter is the greatest Planet in our solar system.

4. That Saturn is the second Planet with regard to magnitude.

5. That Herschel ranks third.

6. That the Earth ranks fourth; but that

7. Each of the other Planets and the Moon are smaller than the Earth.

8. That either of the Planets Ceres, Vesta, Juno, Pallas is smaller than the Moon.

§ 11. If you cut a ball or a sphere in halves, and through the centre of one of the flat surfaces, draw a straight line across the whole surface, then this line is called the Diameter of the ball or sphere.—Now as the Sun and the Planets are nothing else but large balls or spheres (Lesson I, § 4), we may also speak of their Diameters.—Thus we say, “the Diameter of the Sun is so many times larger than that of the Earth; the Diameter of Jupiter is so many times larger than that of Venus,” etc.

You will now easily understand what the straight line means, which, in plate No. III is drawn through the centre of the circle, which represents the Sun; also the straight lines which are drawn through the circles which represent the Planets.—You will also perceive from the first figure on plate No. III, that the Sun’s Diameter is larger than the Diameters of all the Planets taken together.

§ 12. Plate No. IV represents the surfaces of the Planets, compared to that of the Sun.—For you must know that it is possible to measure the surface of a sphere; which is done by supposing it to be spread out, and then seeing how many square inches, feet or yards it contains. This we have supposed to be done with the surfaces of the Sun and Planets, and accordingly, have drawn their square measurements, in Plate No. IV. in proportion to each other.

You will see from this Plate:

1. That the square-Contents of the Sun’s surface is greater than that of the surfaces of all the Planets taken together.

2. That the square-Contents of the Earth’s surface is nearly as large as that of the surfaces of Mercury and Venus taken together.