Alpha Centauri's Universe: Monthly Publication

The phrase "terraforming a planet" is somewhat misleading. Interpreted literally, it ought to mean that another world is to be made similar to Earth.         In practice, that is impossible. No matter what we do we cannot make Mars, Venus, or any other planet of the solar system the same size as Earth, or give it an identical orbit. And if similarities in size and position were the criteria for planetary terraforming, Venus would win hands down. Venus is often spoken of as a "sister world" to Earth. It is only 5 percent smaller in radius and closer to us than any other world except our own Moon. A man or woman who weighs 140 pounds here would weigh 127 pounds on Venus--hardly enough change to notice. But that same person would weigh 370 pounds on Jupiter, 53 pounds on Mars, and a mere 4 pounds on the largest asteroid, Ceres. Why, then, do we not think of terraforming Venus before we consider Mars? It is not enough to say that humans have been fascinated by the red planet, in fact and fiction, for over 100 years, since Percival Lowell's

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