You know the planets of our solar system, each a unique world with its own distinctive appearance, size, and chemistry. Mars, with its bitter-cold, rusty red sands; Venus, a fiery world shrouded in thick clouds of sulfuric acid; sideways Uranus and its strange vertical rings. The variety is breathtaking.
Now imagine the variety that must exist in hundreds of solar systems. There may be worlds out there that make Venus seem hospitable and Uranus positively upright. Only 20 years ago, astronomers were unsure whether any such worlds existed beyond our own solar system. Now, they've found more than 280 of them, each with its own planetary "personality," each a fascinating example of what a world can be.
What we normally mean by a "world" includes intelligent beings. You know, "Shakespeare's world" or "Nefertiti's world" or even "Sherlock Holmes's world" or, at worst, the "dinosaurs' world."
The perceiver of a world is in at least one sense its creator. I would rather not lose that concept.
A researchers hold out little hope, apparently, that the planets they will find are well suited to life. Still, we wait with interest ... And the graphic above, by artist T. Riecken, is pretty neat.