Sunset on Mars is a pale, washed out, watery sort of procedure that is hardly worth looking at. The shadows of the cactus lengthen, the sun goes down without the slightest hint of color or display and everything is dark. About once a year there is one cloud that turns pink briefly. But even the travel books devote more space describing the new sign adorning the Canal Casino than they do on the sunset.

The night sky is something else again. Each new crop of tourists goes to bed at sunrise the day after arrival with stiff necks from looking up all night. The craters of the moons are visible to the na............