Comet Hale Bopp Over the Superstition Mountains . ... Credit Copyright: William R. Dellinges Explanation: Four years ago, Comet Hale-Bopp was discovered out near Jupiter falling toward the inner Solar System . ... Clearly visible are the comets white dust tail that shines by reflected sunlight, and the blue ion tail that shines by glowing gas. ... A comet visible to the unaided eye appears about once every five years. ... NASA Web Site Statements, Warnings, and Disclaimers . ...