Dust and Gas in D/Shoemaker-Levy 9

The spectacular impact of D/Shoemaker-Levy 9 on Jupiter in July 1994 was observed all over the world and from space, leading to many new and exciting clues to the physics of the Jovian atmosphere. However, what do we know of the impactor? There were only 16 months to study D/Shoemaker-Levy 9 between its discovery and destruction. D/Shoemaker-Levy 9 was designated as a comet at time of discovery. Then, due to the apparent absence of volatiles usually present in comets it was repeatedly discussed whether D/Shoemaker-Levy 9 was a comet or an asteroid. Although its true nature can still not be named unambigeously, a cometary origin is indicated from the observational evidence. The results of the dust analysis are consistent with D/Shoemaker-Levy 9 being a typical comet and so far this is not contradicted by any observation.