Amateur astronomers spot comet damage on Jupiter

AMATEUR astronomers in Britain have seen a giant black spot on Jupiter where one of the fragments of Comet Shoemaker-Levy 9 punched a hole in the planet's frozen atmosphere with the force of a billion H-bombs.

They claimed yesterday that the 'blackeye' caused by fragment G as it collided with Jupiter left a clear mark that could be seen with relatively small amateur telescopes.

The black spot is more intense that the Giant Red Spot, a permanent storm raging on the planet, and is estimated to be equal in size to the Earth, which is 300 times smaller than Jupiter.

Robin Scagell, vice-president of the Society for Popular Astronomy, said he was 'absolutely amazed' at being able to detect the impact with non-professional instruments. 'We have never seen anything like this. This is like a science-fiction movie, a dream that keeps going on and on. We've now found the G-spot.'

The black disc could be seen with an 8.5-inch reflecting telescope, Mr Scagell said. It could be massive dust clouds spreading out across the planet, or a burnt-out region of the dense Jovian atmosphere caused by the intense heat of the fireball as the ice and dust of fragment G vaporised.

David Hughes, a lecturer in physics at Sheffield University, said the intensity of the spots left by the fragments of the comet could not be easily explained. If they were dust, the strong winds on Jupiter should have dispersed the impact site more quickly. 'In the end we're learning more about Jupiter than about comets.'

By this morning, 10 of the 21 fragments of Comet Shoemaker-Levy 9 should have crashed into Jupiter. Astronomers are keenly awaiting tonight's encounter with fragment Q1, the biggest, which is expected just before 9pm.

Professional astronomers using Britain's William Herschel Telescope, a 4.2-metre instrument sited in the Canary Islands, yesterday released images of Jupiter clearly showing four impact sites, including that left by fragment G.

Peter Andrews, an astronomer at the Royal Greenwich Observatory in Cambridge, said the 'ejector' material thrown out by the immense impact of the fragments was visible. 'Almost certainly what we can see is a shock wave.'

Telescopes that detect infra-red radiation - heat - are showing structures caused by the fragments that last for far longer than expected, Dr Andrews said. 'Some are lasting for several rotations of the planet.'

The Hubble Space Telescope, parked in an orbit well above the interference of Earth's atmosphere, is producing some of the clearest images of the impacts. But the best data should come from the Galileo space probe on the far side of Jupiter, which has a direct view. Unfortunately Galileo's main transmitting antenna is impaired but scientists hope to collect sufficient data via its secondary transmitter to build up an accurate picture.

Comet Shoemaker-Levy 9 was discovered only last year after it split into fragments following a previous close encounter with Jupiter. It is the first time astronomers have been able to predict an impact between a comet and a planet more than a few seconds before it actually occurred.

(Photograph and graphic omitted)