Comet Elenin’s Last Gasp

Northern skywatchers are longing for a nice, bright comet to grace their skies — the kind of celestial spectacle that Comet McNaught (C/2006 P1) put on a few years ago for those Down Under.

When discovered last December, Comet Elenin (C/2010 X1) had the potential to at least crack the naked-eye-visibility threshold. OK, it was never going to be a McNaught or Hale-Bopp, but we're getting a little desperate up here north of the equator. The prediction was that Comet Elenin's inbound course would loop around the Sun at a distance of just 0.48 astronomical unit (45 million miles) on September 10th, followed by a quick climb into predawn skies for a couple weeks of nice visibility as it passed 0.23 a.u. from Earth in mid-October.

Alas, it was not to be. About 10% of such long-period comets randomly break apart on their first visits to the inner solar system, and Comet Elenin drew the short straw. By April the icy interloper was showing signs of pooping out, and it appeared to completely self-destruct about three weeks before perihelion.

"Disintegrating comets (as opposed to splitting ones) do not survive very long after the process has been observed to begin, which in the case with Comet Elenin was all the way back in the end of August," explains John Bortle, who's tracked the passages of these icy bodies for more than 50 years. "The decline/fade of Elenin was abrupt and dramatic."

Wisps of Comet Elenin
Here's all that remains of Comet Elenin (C/2010 X1), as imaged on October 21 and 23, 2011, using a 4-inch refractor and stacks of twelve 5-minute exposures. A small red X marks the comet's predicted location in each frame. The short streak at far right is the unnamed asteroid 138524 (magnitude 14.5).
E. Guido / G. Sostero / N. Howes
Still, diehard observers have continued to look for the disrupted object's remains, with little success. Juan José González reports spotting a faint, diffuse cloud twice, on October 9th and 21st, from the summit of Alto del Castro (5,600 feet, 1,720 m) in northern Spain. It's a sighting claim that other comet observers, many armed with deep-probing cameras, dispute.

Putting the long-running "visual vs. CCD" debate aside, there's no question that Comet Elenin is — er, was — nothing like the Earth-threatening behemoth proffered by fringy pseudoscientists earlier this year. Using a remote-operated observatory in New Mexico, observers Ernesto Guido, Giovanni Sostero, and Nick Howes managed to record a wispy cloud at the comet's predicted location on October 21st and again on the 23rd. "The 'cloud' is roughly 40 arcminutes long with an extension of 6 arcminutes near the expected position of the comet," notes the report on their website.

In the meantime, comet-starved skygazers can always look to the stars of Hercules, where you'll find Comet Garradd (C/2009 P1) coasting along. It's not going to get much brighter than 7th magnitude, but on the other hand it'll stay nearly that brightness — and in the same region of sky —through January. So download S&T's finder chart, get those binoculars out, and have a look!

3 thoughts on “Comet Elenin’s Last Gasp

  1. Joe Stieber

    1) Shouldn’t that be C/2006 P1 (McNaught) — that’s P1 rather than R1; also, it’s correct nomenclature to put the discover’s name parenthetically at the end.

    2) Should it now be D/2010 X1 (Elenin)? "D" for defunct or disintegrated rather than "C" at the beginning.

    3) I’ve followed the situation on the comet e-groups, and it seems to me that Gonzalez was vindicated. Despite being called (in so many words) a fool or a liar by certain commentators, Gonzalez remained steadfast about his sightings. That’s when the imagers got serious and found pretty much the same cloud he was describing from his visual observations.

  2. Kelly BeattyKelly Beatty

    Joe, thanks for that correct McNaught designation, now fixed. as to nomenclature, the IAU has its formal style conventions and S&T doesn’t always follow those; this is one of those cases. (we don’t put parentheses around an asteroid’s number either.) also, D/ is only used for *periodic* comets that cease to exist.

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