Of all life-bearing worlds, oxygen planets are the rarest and most valuable.
Stars, of course, are as common as dirt, and as filthy with life. Sundwellers as large as Australia and as small as the state of New Jersey infest the surface of even so common a star as our own. A red giant like Aldebaran holds so many living creatures on its surface that it's a wonder any light gets out at all. Most of the leaders and industrialists of the Known Universe come from red giants.
Next after stars come the gas giants. Ammonia atmospheres, for some reason, are particularly conducive to intelligent life. Since ammonia-based life forms are almost universally floaters, lacking even rudimentary manipulating limbs, they lead lives of the mind. Most of the philosophers and theologians of the Known Universe come from gas giants.
Third in line are the vacuum planets. Free of the corrosive effects of an atmosphere, an enormous variety of magnetic, gravitic, and energy-based civilizations have arisen. These are the artisan races—the merchants, mechanics, and artists.
Last of all, and most valued, are the oxygen planets, often called the "Goldilocks worlds" because in order to hold the extensive oceans that make such atmospheres stable, they must be neither too far from their suns nor too near, but can only exist at a "just right" distance.
The oxygen planets are valued for their intelligent species. An oxygen race typically employs tools, shows enormous ingenuity under stress, is fiercely loyal and yet irrepressibly playful, and is capable of being taught almost any skill.
They make great pets.
© 2002 by Michael Swanwick and SCIFI.COM.