Sunday, December 8, 2013

Comet ISON ~ The Perils of Sungrazing

Sadly, Comet ISON did not survive its close encounter with the sun on Thanksgiving Day. At the same time, following its journey live on twitter via existing instruments deployed to observe the sun was a roller coaster ride of celestial excitement. As it approached the sun, ISON brightened, then faded, as would be expected if the sun's heat and intense tidal forces destroyed the nucleus.

The Solar Dynamics Observatory (SDO) did not capture ISON at all at perihelion. The Solar and Heliospheric Observatory (SOHO) and Solar Terrestrial Relations Observatory (STEREO) imaged ISON as a bright nuclues trailing a long coma and a smaller, narrower dust streamer, as it plunged towards the sun. Both SOHO and STEREO, which are not optimized for comet viewing, did not capture ISON during its closest approach to the sun. Once enough time had elapsed for ISON - if it survived - to have rounded the sun and reappear in SOHO images, there was no trace of the comet. Astronomers and the twittersphere reported on Comet ISON's fiery demise, some with sadness, some with humor, as evidenced in twitter comments such as the sun having roast comet for Thanksgiving.

Then, almost 24 hours post-perihelion, it became evident that *something* had rounded the sun, as ISON - or what was left of it - once again appeared in SOHO images. ISON looked much dimmer, more diffuse and with only the faintest of tails, indicating the nucleus had most likely broken up. As the cometary remains sped away from the sun, ISON's brightness faded. Comet ISON was no more - even as it left scientists with a treasure trove of cometary data that will advance our knowledge for years to come.

Below is an animation of SOHO images showing ISON's ill-fated encounter with the sun:

Perhaps ISON has a little different view on all of this:

Image credit:

See previous post below for a collection of beautiful images taken around the world as ISON passed closed to Earth on its way to perihelion in November.