The Gas between the Stars; Extreme Universe; Exclusive Online Issues; by Ronald J. Reynolds; 10 Page(s)

We often think of the moon as a place, but in fact it is a hundred million places, an archipelago of solitude. You could go from 100 degrees below zero to 100 degrees above with a small step. You could yell in your friend's ear and he would never hear you. Without an atmosphere to transmit heat or sound, each patch of the moon is an island in an unnavigable sea.

The atmosphere of a planet is what binds its surface into a unified whole. It lets conditions such as temperature vary smoothly. More dramatically, events such as the impact of an asteroid, the eruption of a volcano and the emission of gas from a factory's chimney can have effects that reach far beyond the spots where they took place. Local phenomena can have global consequences. This characteristic of atmospheres has begun to capture the interest of astronomers who study the Milky Way galaxy.