Science: The Moon's Atmosphere

A favorite diversion of amateur astronomers is to watch the moon eclipsing a star. When the star touches the moon's jagged edge, it winks out all at once with no preliminaries. Even the delicate instruments of professional astronomers cannot detect the slightest trace of dimming or wavering. But if an astronomer on the moon were to watch the earth eclipsing a star, he would see a different performance. The star would grow dim and reddish like the setting sun, and its light would be bent by refraction in the earth's atmosphere, making the star appear to shift its position.

The absence of...