The long ion tail of comet Wilson

The long ion tail of Comet Wilson. This photo of Comet Wilson was obtained with the ESO 1m Schmidt telescope on March 28, 1987, three weeks before its closest approach to the Sun (perihelion). It shows the development of a long, weak ion tail, consisting of ionized atoms and molecules which are pushed away from the coma (comet head) by action of the solar wind. This straight ion tail measures about 3 degrees, corresponding to about 11 million km (projected) and points towards southwest. Note also the streamers near the coma. A short, stubby dust tail is seen towards north (to the left in this picture).