Astronomers around the world are monitoring the break-up of comet Linear, which was recently a fine sight in binoculars.

It is believed that intense solar heating when the comet rounded the Sun triggered a massive disruption of the comet's fragile icy core.

But even on the day before perihelion, it was clear that the comet was in trouble as it approached within 114 million km (70 million miles) of the Sun.

"The very first images on July 25th were enough to show me that something odd was going on," said Dr Kidger. "The comet's inner coma was no longer teardrop-shaped. It had a shape like a short, fat cigar. My first thought was Shoemaker-Levy. It looked just like those first images of Comet Shoemaker-Levy 9 after it was discovered."

Meteor shower

Alerts were sent around the world to astronomers to look at the fragmenting Comet Linear.

But unlike Comet Shoemaker-Levy 9, which broke into many well-defined bright fragments, Linear seems to be dissolving into an amorphous haze of gas and dust.

"The small size of comet Linear and its exposure to solar radiation is causing a more complete and rapid dissolution than we saw in Shoemaker-Levy 9," said Brian Marsden of Harvard's Minor Planet Center in the US. "Comet Linear will probably have completely dispersed in a week or so."

Dr Kidger added: "The surface brightness of the innermost coma is fading fast."

Many well-known annual meteor showers, including the Perseids, are caused by dusty debris from comets burning up in the atmosphere of Earth.

However, because of this comet's orbit, there will be no "Linearid" meteor shower. When it finally disappears in a few days, this visitor from beyond the orbit of Neptune will be gone forever.