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We are grateful to M. Britton for follow-up observations at Palomar and to P. Goldreich, T. Ahrens, and M. Pritchard for insightful discussions. J.L.M. thanks S. Kulkarni for financial support. Some of the data presented here were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The observatory was made possible by the generous financial support of the W. M. Keck Foundation. We extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, many of the observations presented here would not have been possible.