Is the ‘Christmas Comet’ cracking up?

  

photo: Reuters

An incoming comet that skygazers had hoped would provide one of the greatest celestial shows of the century, could be a fizzle.

So say astronomers tracking the eagerly-awaited Comet ISON as it races to a searing encounter with the Sun.

WHAT IS ISON?

Formally known as C/2012 S1 (ISON), the comet was spotted by a pair of hard-working amateur Russian astronomers on September 21, 2012.

It is called ISON because they used a telescope called the International Scientific Optical Network near Kislovodsk, in the northern Caucasus.

WHY IS IT INTERESTING?

After the discovery was validated by the International Astronomical Union (IAU), interest in the enigmatic wanderer became huge.

Calculations showed that after looping around the Sun, the comet would become a blaze of glory towards the end of the year — a timing that gave it the tabloid title of “Christmas Comet” or even “Comet of the Century.”

WHAT HAPPENED NOW?

Fears are multiplying that the great show will be cancelled.

Light signatures from ISON, which has just streaked past Mars, indicate the comet is about to break up, says astrophysicist Ignacio Ferrin. “This disintegration will take place before it reaches perihelion,” Ferrin said. Perihelion is an orbit’s closest point to the Sun, which ISON is supposed to reach on November 28.

He explained that comets typically brighten as they get closer to the Sun, crossing a temperature threshold that causes their icy surfaces to evaporate, depositing water vapour, other gases and dust in their wake.

But, said Ferrin, the light curve from ISON slowed down and then remained practically constant, with no sign of greater brightness, as it raced forward.

This is a signature that matches four previous comets that have broken up catastrophically, he said.AFP

Courtesy with: THE HINDU