Science has told us too much about the moon that it is fairly easy to imagine what it would be like to get there. It is certainly not a friendly place. Since there is no air or water, there can be no life of any kind. There is not much variety of scenery either. For mile after mile there are only flat plains of dust with mountains around them. Above, the sun and stars shine in the black sky. If you step out of the mountain shadow, it means moving from the severe cold into intense   heat. These extreme temperatures break rocks away from the surface of the mountains. The moon is also a very silent world, for sound waves can only travel through air. But beyond the broken horizon, you see a friendly sight. Our earth is shining more brightly than the stars. From this distance, it looks like an immense   blue, green and brown ball. The best title for the passage is    _    .
An Unfriendly and Friendly Place The Geography of the Moon Moon, a Silent World The Moon