This unnamed crater chain is one of the longest of 12 or so such chains on 
Callisto, one of Jupiter's 4 planet-sized satellites.  It is 360 
kilometers long and the largest individual crater is approximately 24 
kilometers across.  Jay Melosh and Paul Schenk, reporting in the October 21, 
1993, issue of Nature, propose that these and similar mysterious crater 
chains on Ganymede and Callisto probably formed from the past impact of 
comets tidally disrupted during close passage of Jupiter, similar to
comet Shoemaker-Levy 9 which will strike Jupiter in July, 1994.  They 
conclude that tidal splitting of comets is relatively common and can occur 
roughly once per century.

photo credit:  Paul Schenk/Lunar & Planetary Institute

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