Abstract
A wavy structure in the near tail of Comet Halley was observed in Tonantzintla on April 12, 1986. Recent spacecraft encounters with comets have confirmed the Alfven field line draping model of cometary tails. On the basis of this result, the origin of the structure is discussed by considering an equilibrium which consists of a neutral current sheet with a nonvanishing amount of magnetic flux through it. It is proposed that the observed structure is a consequence of the onset of a collisionless tearing instability in the above mentioned plasma equilibrium. Such a magnetic reconnection process could be triggered by an interplanetary shock.
