Astronomy Picture of the Day

Explanation: As Comet Ikeya-Zhang approached the Sun two months ago, it developed a complex blue ion tail. The tail was composed of ions that boiled off the nucleus and were pushed away from the Sun by the out-flowing fast-moving particles of the solar wind. Complexity in the tail is created by comet nucleus rotation, variability in the comet surface evaporation rate, and variability of the Sun's magnetic field and solar wind. The above animation documents how Comet Ikeya-Zhang's tail changed over 30 minutes in ten consecutive 3-minute exposures on March 11. Comet Ikeya Zhang is now fading as it heads back to the outer Solar System. It should remain visible through a small telescope for another month.