  Stephan's Quintet (SQ) is a compact group that we find in an atypical moment
when a high velocity intruder is passing through it. The intrusion is
particularly interesting because a previous intruder had stripped most of the
gas from the group members. This debris field was shocked in the ongoing
collision with the new intruder. This evolutionary history agrees well with
observations and explains how a strongly interacting system can show low levels
of star formation. We present new multiwavelength data including previously
unpublished ROSAT X-ray, Ha interference filter/FP, ISO MIR/FIR and radio line
and continuum images. These observations and previously published data provide
new insights as well as support for some previous hypotheses. 1) FP and HI
velocities allow us to unambiguously distinguish between gas associated with SQ
and the new intruder.
  2) Most detected emission regions are found in the remnant ISM of the NI
which allows us to infer its size and present physical state. 3) The few
emission regions associated with the stripped ISM of SQ include the best
candidate tidal dwarf galaxy. 4) Multiwavelength data suggest that strong
MIR/FIR emission from the Seyfert 2 nucleus of NGC7319 comes from dust heated
directly by a power-law continuum rather than a starburst. 5) The
correspondance between extended X-ray/radio continuum/forbidden optical
emission confirms the existence of a large scale shock in SQ.
