29 Nov 2013

Sun shreds big comet into fizzer

5:38 pm on 29 November 2013

A large comet which astronomers had hoped would light up the night skies before Christmas appears to have disintegrated in a close encounter with the sun.

Telescopes showed comet Ison disappeared behind the sun but only a dull streamer emerged, the BBC reports.

The comet had been travelling through space for five and a half million years but is thought to have been destroyed by the sun's heat and gravitational field.

Astronomer Matthew Knight was watching it from the Kitt Peak Observatory in Arizona, and says that the observations of the comet are unique.

"We're never seen a comet which all the way from the Oort Cloud - the edge of the solar system - to the very edge of the sun like this ... because it got so hot, it was literally melting the rocks. They were coming off as dust, and these rocks were turning into gas".

No brilliant tail

The giant ball of ice, rock and dust disappeared behind the Sun, but only re-emerged as a dull streamer, and astronomers found that the comet had gone out with a whimper.

Ison had captivated skywatchers with its promise ever since it was discovered by Vitali Nevski and Artyom Novichonok in 2012.

A "fresh", 2km-wide object flung in towards the inner Solar System from its home far beyond the outer planet Neptune, it was hoped it might produce a brilliant tail that would arc across the night sky, perhaps for weeks.

As it got closer and closer to the Sun, its ices did begin to vaporise, releasing dust that shimmered in a distinctive trailing stream.

But from early on, it was clear Ison was unlikely to be spectacular; it was just not brightening in the way experienced comet watchers had anticipated.

The European Space Agency's experts used the Soho Sun-watching satellite to track Ison as it began its sweep around the back of the Sun, saw only the last fizzling of debris as it re-emerged.