Worlds in Collision was met with derision from scientists. Among other problems, the composition of Venus and Jupiter are quite different, and the energy required for ejecting so much material would have vaporized the nascent planet. At a 1974 debate sponsored by the American Association for the Advancement of Science, Carl Sagan, the popular astronomer, was among the panelists opposing Velikovsky. But the attacks may have strengthened Velikovsky's standing; he struck some people as an underdog fighting the scientific establishment.
Velikovsky's ideas seemed radical a half century ago—most astronomers assumed that planetary change occurred at a slow, constant rate. His remaining adherents point to the asteroid impact that killed most of the dinosaurs 65 million years ago as evidence he was ahead of his time.
Erik Washam is the associate art director for Smithsonian.