In the Star Wars sci-fi saga, the fictional planet Bespin is an immense gas giant surrounded by a number of moons. It contains a band of habitable atmosphere among the clouds. This is where Cloud City is located, a mining colony set up to extract valuable Tibanna gas.

"I don't know what Tibanna gas might be," said Seth Shostak, a real-life astronomer with the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California. "Gas-giant planets seem to be swathed in ammonia, methane, and other vapors that, frankly, are neither rare nor particularly valuable. They are useful for cleaning the bathroom or cooking dinner, of course."

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