‘Christmas Comet’ could break up and fizzle out: scientists


Sun, Oct 20, 2013 - Page 6

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.




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

However, fears are multiplying that the great show will be canceled.


“This disintegration will take place before it reaches perihelion,” Ferrin said in an e-mail.

Perihelion is an orbit’s closest point to the Sun, which ISON is supposed to reach on Nov. 28.

“There are also predictions for disintegration at perihelion, but based on the evidence, the comet will not get there,” Ferrin said.

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

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



Comets are believed to be huge clusters of primeval dust and frozen ices, including water and organic molecules that, some say, delivered the building blocks of life to the infant Earth.

Doomed to orbit the sun in periods that can range from years to many millennia, comets undergo thermal stress as they near the star.

Veterans that make short-period flybys, such as Halley’s Comet, appear to have a crust of silicates and “tarry” carbon molecules to insulate them from the heat.

However, rare visitors such as ISON have no such protection, Steel said.