Diane Andrew, aged 11, of Denver,, Colo. for her  question:

Why don't the other planets have air around them?

The earth is not the only planet to wear a blanket of atmosphere. However, so far as we know, it is the only planet to have our special mixture of air. It may well be the only planet with enough oxygen in its air to support life as we know it.

The atmosphere of Mars contains some oxygen, though not nearly enough to keep us comfortable. Venus is veiled in a thick blanket of clouds and atmosphere, So thick are the veils that no telescope has yet seen the face of Venus of even its lower atmosphere.

The big planets, Jupiter, Saturn, Uranus and Neptune also have atmospheres. However, the air is very different from our gentle life‑giving blend of gases. Which is lucky for us. Their gases are harmful and even poisonous to our kind of life. These atmospheres are composed chiefly of two gases ‑ ammonia and methane. Ammonia is definitely dangerous and methane is the marsh gas or natural gas we use for cooking, There is no oxygen on these bitter cold planets.