LOS ANGELES - Scientists think they have solved the mystery of how planets form around a star born in a violent supernova explosion, saying they have detected for the first time a swirling disk of debris from which planets can rise. The discovery is surprising because the dusty disk orbiting the pulsar, or dead star, resembles the cloud of gas and dust from which Earth emerged. Scientists say the latest finding should shed light on how planetary systems form. "It shows that planet formation is really ubiquitous in the universe. It's a very robust process and can happen in all...