The development of the plasma tail of comet Austin 1990 V on four cons
ecutive CCD-images on May 6 1990 (Bonev & Jockers 1994) looks striking
ly similar to the results of timedependent three-dimensional MI-ID cal
culations modeling the effect of a sudden rotation of the interplaneta
ry magnetic field (IMF) by 90 degrees (Rauer et al. 1995). Assuming th
at the changes in comet Austin's tail were in fact generated by a sudd
en rotation of the IMF one can infer the three-dimensional structure o
f the tail under stationary solar wind conditions. The results are dis
cussed and compared with MHD models.