ISON Obituary

By Elise Ricard

Right now, about the time we would have been seeing comet ISON in its full blaze of glory, returning to the outer solar system after skimming the Sun, we are instead wistfully piecing together the details of how it met its demise.

After over a year of anticipation and intense media hype surrounding the potential “comet of the century,” ISON peaked in its brightness at magnitude –2.0 on November 27th, then started to fade before it even rounded the Sun.

The first official reports of the comet’s demise were made late on November 28th, although there was uncertainty for a few days when the Solar and Helospheric Observatory (SOHO) captured images of ISON with a thin dusty tail and a diffuse central condensation. Hopeful observers interpreted this as a small remnant of the comet’s nucleus. But did the nucleus of the comet survive?  As it turns out, no.

To be fair, the comet did skim within 724,000 miles of the Sun’s surface, actually putting it through the Sun’s outer atmosphere. Not much would survive that.

Comet ISON began its life in the outer solar system some 4.5 billion years ago, orbiting the Sun from afar until the Sun’s gravity pulled the “dirty iceball” in. The comet was first detected on September 21st, 2012, by Russian astronomers Vitali Nevski of Belarus and Artyom Novichonok, via the telescopes of the International Scientific Optical Network (ISON). While estimates of its potential brightness were overblown by media from the beginning, we kept a careful eye on the comet for over a year. The closer it got to the inner solar system, however, the less hope astronomers had for it surviving its trip around the Sun, let alone dazzling onlookers with a bright and brilliant display. Sadly, they were correct.

But this kind of “disappointment” happens all the time. One of the amazing things about science is that things very often do not go as planned (or desired) but yield far more interesting results.  So, although many were disappointed by the lack of show, ISON leaves behind a legacy of what Naval Research Laboratory’s Karl Battams calls “the largest and broadest cometary data set in history, compiled by more ground and space-based telescopes than ever before.”  This included data on ISON’s composition and interaction with environs. The positive results were not just data-based, however—ISON captured public attention in a way no other comet has since Halley in 1986—getting the public excited about science is never a bad thing.

ISON’s official obituary was composed by Battams last week and confirmed at this week’s American Geophysical Union (AGU) Meeting. No memorial service is planned, although “donations are encouraged to your local astronomy club, observatory or charity that supports STEM and science outreach programs for children” and visits to your local planetarium are always encouraged.

Elise Ricard is the Senior Presenter at Morrison Planetarium and holds a master’s degree in museum education.

Image: NASA