human
Ah, Doctor, I am so glad you have wakened. I am frightened, terrified, by the light!
gpt
Light! Where have you seen any light?
human
I saw the Earth begin to shine like a New Moon on the eastern edge, but----
gpt
Ah, that _was_ a danger signal. I am glad you awakened me. But you are actually pale and trembling! There is no danger if you keep the course. You see, that rim of light has faded and disappeared since I corrected the course.
human
Yes, but you cannot keep in this little Earthly shadow much longer; and what can we possibly do when we emerge into the fathomless, trackless effulgence of eternal sunshine? Let us turn back before we plunge into it,
gpt
So that is what terrified you! Well, you have hit upon one of the greatest difficulties of the trip; but it is far from insurmountable. We will not turn back yet, especially as we have started in the most opportune time. You have mentioned this 'little shadow.' It is eight thousand miles wide at the surface of the Earth, and gradually, very gradually, tapers down to nothing far out in space. Have you ever calculated how far it reaches?
human
No, I answered.
gpt
But we moved out of it and back into it at the surface very easily, and besides, as the Earth moves forward in its orbit, the shadow will leave us.
human
This little shadow is eight hundred and fifty-six thousand miles long, and we will never leave it as long as it lasts! exclaimed the doctor.
gpt
Just at this time it points like a long arrow out in the direction of Mars. It is moving gradually as the Earth moves and hourly correcting its aim. At opposition time it will point directly and unerringly at Mars. Therefore it is a way prepared, surveyed, and marked for us through the all-enveloping sunlight, which otherwise would be dreadful enough.
human
But how can we be sure of keeping in it? It is rapidly narrowing as it reaches farther out.
gpt
I see I should have explained that to you before I went to sleep, and saved you this fright. The shadow now points behind Mars, as it is many days yet before it overtakes that planet in opposition. That is why I told you to steer always a little behind the planet. But you went a little out of the course, and immediately something warned us. That rim of light on the east of the Earth was notice to us that we were not in the centre of the shadow, but bearing too far to the left. We must keep absolutely in the dark of the Earth, with no light visible on either side of it. If a thin rim should appear on one side, we must turn toward the other until it is all dark again.
human
Grant that this shadow is so enormously long, yet it is only scarcely one-fortieth of the distance to Mars, I objected.
gpt
After we emerge from it, what then?
human
With the aid of my telescope we shall probably be able to see the Earth as an orb, half or quarter as large as the Moon usually appears to us, and to observe its phases until we are several million miles from it. We must continue to keep the rim of light, which will then surround it, equal on all sides.
gpt
Ah, but I am afraid, I interrupted,