The Study of Astronomy, adapted to the capacities of youth / In twelve familiar dialogues, between a tutor and his pupil: explaining the general phænomena of the heavenly bodies, the theory of the tides, &c.

by teacher of astronomy John Stedman

Pupil. Then the light we receive from the sun is by reflection conveyed to the other planets.

Tutor. No doubt of it. And our earth appears as a moon to the inhabitants of the moon, and undergoes the various changes of that planet.

Pupil. Have you any proof of this, Sir?

Tutor. Nothing can be clearer; for, on a fine evening, soon after the change of the moon, when the earth appears nearly as a full moon to the moon, and we see a faint streak of light, the whole body of the moon is visible to us.

Pupil. I remember to have seen it.

Tutor. You do?—The earth then will appear there thirteen times as large as the moon does to us; of course it must reflect a strong light on the body of the moon, and it is by that light we see that part of the moon which is turned from the sun.

Pupil. Is the earth, then, only thirteen times as big as the moon?

Tutor. In solidity it is about fifty times as large; but its disc or face is only thirteen times.

Pupil. What is the moon’s distance from the earth?

Tutor. 240 thousand miles, which is about 400 times less than that of the sun.