Apparently it was quite dense as to be able to survive the Venetian atmosphere so there has been speculation it may stay somewhat intact.
That one means "having to do with Venice". Of Venus would be "Venusian", "Venereal" (yes, really), or "Cytherean". Or, one of a dozen others—it's a Greek god-name; there's millennia of culture to drawn on.
There's an entire Wikipedia entry devoted to this adjective question,