Astronomy Picture of the Day

Explanation: What's happening to Comet Hale-Bopp's blue ion tail? The comet's ion tail is fluctuating more rapidly as it passes a region of changing solar wind. As the comet passes from north to south, it crosses the plane of the Sun's equator, where the solar magnetic field changes direction. Ions from the solar wind, which cause Comet Hale-Bopp's ion tail, act unpredictably here. Therefore, Comet Hale-Bopp's ion tale may show unusual structure or even a disconnection - where the tail appears to break off and then reestablish itself later. The above picture, taken April 30th, indeed shows unusual structure in the blue ion tail.