In this task, you're given an article and an answer. Your task is to generate the fill-in-the-blank question for this answer based on the given article. The blanks are always at the end of the question, and can be filled with more than one word or phrase.

Article: 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.
Answer: all of the above
The moon is an unfriendly place because _ .