 Astronomers estimated that the visible fragments of SL9 ranged in size from a few hundred metres to two kilometres across , suggesting that the original comet may have had a nucleus up to 5 km ( 3 @.@ 1 mi ) across — somewhat larger than Comet Hyakutake , which became very bright when it passed close to the Earth in 1996 . One of the great debates in advance of the impact was whether the effects of the impact of such small bodies would be noticeable from Earth , apart from a flash as they disintegrated like giant meteors . The most optimistic prediction was that large , asymmetric ballistic fireballs would rise above the limb of Jupiter and into sunlight to be visible from Earth . Other suggested effects of the impacts were seismic waves travelling across the planet , an increase in stratospheric haze on the planet due to dust from the impacts , and an increase in the mass of the Jovian ring system . However , given that observing such a collision was completely unprecedented , astronomers were cautious with their predictions of what the event might reveal . 
