Rebecca Coss, of Nga Tawa School, asks :-

What happened when the comet Shoemaker-Levy collided with Jupiter?

Rod Austin, a newspaper photolithographer and an amateur astronomer who has discovered three comets, all of which are named after him, responded.

As comets move slowly against the background stars, it takes many weeks for sufficient observations to be obtained to determine exactly what a comet will do. Comet Shoemaker-Levy 9 was actually discovered on March 24 1993, probably more than twenty years after it had been captured by Jupiter and eight months after its previous close approach to Jupiter during which the large gravitational forces had broken it up into many pieces, some about a kilometre across and each similar to a 'dirty snowball'.

Over a few days in July of 1994 the very large pieces of the original nucleus, now travelling at a speed in excess of 200,000 kilometres per hour, buried themselves deep into the atmosphere of Jupiter before the extreme temperatures and pressures caused them to explode like gigantic depth-charges. Each explosion caused huge volumes of gas from deep in the atmosphere to burst to the surface after several hours, causing huge dark markings to appear in the upper atmosphere of Jupiter. These were most impressive in even quite small telescopes. Some of the areas were larger than the Earth, and the volume of atmosphere affected probably exceeded the volume of all the water in the Pacific Ocean.

It is a timely reminder of what has happened on Earth in the past, and will eventually happen again.