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Thu, 05 Dec 2013 - Comet ISON : the rise, fall, rise & fall

Sadly it seems that Comet C/2012 S1 ISON did not survive its perihelion passage and hence it won't become an impressive naked eye comet in the December night sky.

Concerns were raised when the comet appeared to start to fade just before perihelion and, initially, it wasn't visible in the post-perihelion images from the SOHO spacecraft.

In the hours that followed however, something fairly comet-like was seen following the expected orbit and this brightened dramatically over the next day, becoming much brighter than 1st magnitude Antares. Hopes were raised that a fragment of ISON had survived and the comet would soon become visible in the morning twilight.

Sadly, over the following 24 hours the "object" faded dramatically as it moved further out from the Sun.

Comet experts now face the challenge of explaining exactly what happened. The likelihood is that the comet started to break up before perihelion, but did a small fragment survive perihelion, or were we just seeing sunlight reflecting off a dispersing cloud or debris?

Below is a composite of images (credit: ESA, NASA) from the SOHO spacecraft which shows how the comet initial brightened post-perihelion, but then fades out as it moves towards the edge of the field of view. 


Added by: Tracie Heywood