Cinda Lou Fulton, age 11, of Washington, Ill., for her question:

What is the difference between the atmosphere and space?

The atmosphere is the shell of filmy gases which blankets our green globe. Space begins high above our heads where the atmosphere ends, But there is no definite line where this happens. There is a region of no‑man's land which belongs to neither,

The air is most dense near the ground, if we fly straight up, the atmosphere around us gets thinner as we go. lair on top of Mt. Everest, five miles up, is so thin we need a greater supply of oxygen. Higher and higher the air gets thinner and thinner, and ten miles up we could not survive at all without extra oxygen. The region where the air is almost as thin as empty space may be 100 miles above our heads and we  consider  100 miles above the earth to be “space”.