Collision in space

COME mid-July and the moon could bloody well disintegrate and not attract more than passing attention: the world's major telescopes will be focused devotedly on an unique celestial spectacle -- 31-odd pieces of a giant broken-up comet smashing into the dark side of Jupiter. The crash, which will heave into Earth's view -- thankfully, Jupiter spins fast -- within 10 minutes of the collisions, will provide astronomers with a rare opportunity to watch and study the forces that could have helped to form the solar system.

The imminent collision of the comet, Shoemaker-Levy 9, and the gas giant which will take place over about 6 days starting July 18, has proved to be a heaven-sent opportunity for Indian planetaria to pep up their tedious, unimaginative space shows with something far more spectacular. Both the Nehru Planetarium in the Capital and Jaipur's B M Birla Planetarium are preparing for the anticipated rush. Says Nirupama Raghavan, director of the Nehru Planetarium, "This is a pretty important event." Besides giving people a chance to get a close peek at the aftereffects of the collision, slide shows, exhibitions and lectures have been planned.

The Nehru planetarium is setting up several 8- and 13-inch telescopes for the public. In addition, 18 city schools have been supplied with 7-inch telescopes. Students will be called to the planetarium in batches and instructed on how best to watch the tiny cosmic body puncture the giant gasbag. "If the event is dramatic, the kids will be able to locate it," says Raghavan.

The planetarium is also putting up a "cosmic crash" exhibition. It will include a supercomputer-simulated depiction of the probable effects of the cometary wallop of Jupiter, art works, and pictures of the planet that the Voyager flyby had sent.

In Jaipur, the Birla Planetarium has prepared a 10-minute presentation on the "celestial impact". The public will watch the David and Goliath encounter through the planetarium's telescopes. Director Rajmal Jain has also started a series of lectures on the cosmic event.

The SL-9 comet was discovered in March last year by Carolyn and Eugene Shoemaker and David Levy. Not much is known about the origin of the comet, but it has orbited Jupiter for the past decade, having been "captured" by the planet's massive gravity as it flitted around in space. In July, 1992, on its closest encounter with Jupiter, the comet split up into 21 pieces.

This "celestial string of pearls" will plunge into Jupiter's southern hemisphere and, according to Raghavan, will unleash the detonative power of a quarter million megatons of TNT. Raghavan says the cosmic whack could belch out a huge cloud of water vapour or send dust from the exploding fragments hurtling over the planet's cloud cover. Illumination from the anticipated explosions will be reflected off Jupiter's satellites and the flashes can be seen from Earth with 5-inch telescopes.

Whatever happens, Raghavan is optimistic the collision will be an out-of-this-world experience. "If the final 'show' is really interesting," she says, "we will upgrade and extend our exhibition, possibly making it audiovisual."