| |

It’s dead! It’s alive! Did something survive?

You’ve probably heard about the famous sun-grazing comet ISON, which made its closest approach to our local star on Nov. 28. But over the Thanksgiving holiday break, many people were suffering from food coma and family drama to pay super close attention to the heavens. Conflicting reports have been appearing all over the internet. So what exactly happened to ISON?

First of all, what is this comet and why do people care so much about it? ISON (officially named C/2012 S1) was discovered last year when it was six times farther away from the sun than the Earth is. The comet appeared very bright in telescopes at the time, leading to speculation that as the object approached the sun, it would perk up dramatically and make for a spectacular show. Some models suggested ISON might eventually be visible during the daytime, making it a comet you might one day tell your grandkids about. When it finally became visible to the naked eye two weeks ago, expectations and excitement were running high.

On Thanksgiving day, ISON swept around the sun while scientists and comet-watchers waited to see the aftermath. The sun’s intense heat could vaporize the icy body or, if ISON was large and stable enough, it could reemerge and billow out tons of dust, creating a bright spectacle.

Immediate reports suggested that the comet had not survived its solar close-up, “leaving nothing left to light up the night,” as Tracy Vogel at Hubble’s ISON blog wrote. Many news reports pronounced ISON dead.

But then: a Thanksgiving miracle! A faint smudge appeared in telescope images, which grew in brightness to reveal that something had survived. Comet ISON was resurrected, or maybe it was a zombie comet. The unexpected turn of events underscored just how unpredictable comets typically are.

“We have a whole new set of unknowns, and this ridiculous, crazy, dynamic and unpredictable object continues to amaze, astound and confuse us to no end,” wrote Karl Battams on NASA’s comet ISON website on Nov. 28.

Researchers struggled to make sense of all the evidence. There were no clear answers, hence the internet’s constant confusion. Something had emerged from the sun after ISON went around it. But all the signs pointed to the idea that this something was just a fragment or possibly bunch of fragments from a disintegrated comet. And it was highly doubtful that any of these chunks would be visible to the naked eye from Earth. The final story of ISON probably remains to be written but this morning NASA’s ISON blog officially declared the comet dead.

In an obituary, Battams wrote:

“Never one to follow convention, ISON lived a dynamic and unpredictable life, alternating between periods of quiet reflection and violent outburst. However, its toughened exterior belied a complex and delicate inner working that only now we are just beginning to understand. In late 2013, Comet ISON demonstrated not only its true beauty but a surprising turn of speed as it reached its career defining moment in the inner solar system. Tragically, on November 28, 2013, ISON’s tenacious ambition outweighed its ability, and our shining green candle in the solar wind began to burn out.”

The remaining fragments from ISON will likely fade in brightness as they leave the sun. Amateur astronomers may still capture these leftovers in their telescopes but the chances of a once-in-a-lifetime sky show are pretty much gone. Researchers managed to get tons of great data about ISON’s life, which will likely feed studies for many years.

Images: Two views of ISON as it rounds the sun. On left is the comet from NASA’s STEREO Ahead spacecraft while at right is the view from the STEREO Behind spacecraft. A small fragment can be seen to survive in both views. NASA/NRL.