May 15, 2014. Robert Krulwich/NPR. Poor Johannes Kepler. One of the greatest astronomers ever, the man who figured out the laws of planetary motion, a genius, scholar and mathematician — in 1611, he needed a wife. The previous Mrs. Kepler had died of Hungarian spotted fever, so, with kids to raise and a. A sexist double standard. That’s because a man dating a much younger woman is far more common…