Inconstant Star is a science fiction fix-up novel by American writer Poul Anderson. It is formed by the novellas Iron and Inconstant Star, first published in The Man-Kzin Wars (1988) and Man-Kzin Wars III (1990), respectively. The title is from the tumbling alien artifact that sends out radiation. Due to the tumbling effect, the output can only be seen briefly from a given point in space, looking like a star, but then disappearing as the artifact moves.