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A Holiday Curiosity

I just have time this morning to get off one more post before Christmas, although it’s a close call. I’ve got family coming over at mid-day for the first of two holiday gatherings and, because I’m an inveterate baker, I have sourdough bread to attend to. Sourdough (or as my guru Peter Reinhart likes to call it, ‘wild yeast bread’) appeals to me because of its slow rhythms, multiple builds and lengthy rise times, and I’ve enjoyed cultivating local yeasts for both a white and rye starter that I use constantly. Sometimes breadmaking is a wonderful change of pace from keyboarding — you put the mind in neutral for a while and start kneading a mass of dough, a wonderfully Zen-like experience.

The story I wrote this morning is below, but let me take this chance to wish all of you a happy holiday! Centauri Dreams relies on a reader base that has been active and engaged from the start, and I’ve found my thoughts on interstellar issues challenged, shaped and stimulated by our continuing discussions. Looking back, it’s been over six years and 2,000 posts (this is actually the 2,023rd) since I began this site, thinking to turn it into nothing more than a personal database to keep up with news on interstellar issues. It’s now become a career of its own, and I owe that to its readership.

Asteroid or Comet?

And now to business, and the fortunes of the curious object known as (596) Scheila, long thought to be an asteroid but now showing distinct cometary symptoms. Discovered in 1906, Scheila is out of the ecliptic plane and was, in fact, mistakenly identified as a new comet by Steve Larson, senior staff scientist with the Catalina Sky Survey. Long-time Centauri Dreams readers know that the CSS is all about searching for potentially hazardous asteroids, which is what Larson was doing when he ran across the mutable object. The comet identification seemed a natural, says Larson:

“Its brightness of a total magnitude of 13.4 visual, which is about 900 times fainter than the faintest star you can see in a clear, dark sky, led me to suspect that it was a known comet, but I checked the comet database and got nothing.”

Once identified as an asteroid, Scheila was found in the CSS archives, revealing a December 3 image that showed a slightly diffuse object, but not quite the distinctly cometary bright core with faint tail that Larson saw eight days later. Scheila has been analyzed before and found to be made of carbonaceous material left over from the earliest days of the Solar System. Is Scheila, then, an extinct comet that has somehow come back to life? Sorting that out demands the closer look now being given, to determine whether that ‘tail’ is made up of cometary gas and ice or simply dust associated with a collision with another asteroid. Results so far are inconclusive.

Image: The International Space Station is a streak behind the CSS’ 60” dome operated by Steward Observatory (University of Arizona) in the Catalina Mountains north of Tucson. Credit: CSS/UA/Full Moon Photography.

An asteroid collision is interesting, to be sure, but a comet would stand out, as Larson notes:

“Most asteroids are collision fragments from larger asteroids and display a range of mineral composition. But a fraction are thought to be former comets whose volatile ices have been driven off by the sun. If the activity in Scheila proves to be cometary in nature, this will be only the sixth known main-belt comet, and about 100 times larger than previously identified main belt comets.”

Meanwhile, it’s reassuring to know that the Catalina Sky Survey, with telescopes in Arizona and Australia, is out there doing its job. CSS says that it is discovering 70 percent of the near-Earth objects that might pose a threat. Remember the background: A 1998 congressional directive instructed NASA to identify objects 1 kilometer and larger to an estimated confidence level of 90 percent or better. In June of 2006, that mandate was extended to include 140-meter or larger bodies at the same confidence level. The CSS works with the separate Mt. Lemmon and Siding Springs Surveys — all three operating under the name of the Catalina Sky Survey — to sustain the investigation.


Comments on this entry are closed.

  • Bill B. December 24, 2010, 11:15

    Merry Christmas and Happy Holidays Paul, Centauri Dreams contributors, and fellow readers!

  • djlactin December 24, 2010, 12:40

    To all: happy solstice and a felicitous perihelion!

  • bigdan201 December 24, 2010, 13:48

    Indeed, Merry Christmas to all. I too appreciate the consistent content of Centauri Dreams – this is one of the few blogs I check regularly, and I get my daily dose of space from here.

    This sounds like an interesting case. However it turns out, it just goes to show that keeping track of solar system objects pays off – not only in being prepared for possible earth-bound asteroids, but science in general.

    also, Ad Astra Incrementis. It’s a far more encouraging phrase than many other mantras in history (sieg heil, banzai, deus vult, to name a few)

  • Carl Keller December 24, 2010, 13:53

    “We ought to observe also that even the things which follow after the things which are produced according to nature contain something pleasing and attractive. For instance, when bread is baked some parts are split at the surface, and these parts which thus open, and have a certain fashion contrary to the purpose of the baker’s art, are beautiful in a manner, and in a peculiar way excite a desire for eating.” — Meditations, Book III, 2, Marcus Aurelius.

    And: “Everything harmonizes with me, which is harmonious to thee, O Universe. Nothing for me is too early nor too late, which is in due time for thee. Everything is fruit to me which thy seasons bring, O Nature: from thee are all things, in thee are all things, to thee all things return.” Book IV, 23.

    Happy breadmaking, Paul!

  • James M Essig December 24, 2010, 14:56

    Merry Christmas and a great and wonderfilled New Year to you Paul and Marc Millis, as well as the same to all of the other Folks at Tau Zero and Centauri Dreams and the Readership and Commentors to Centauri Dreams.


    The sourdough bread looks delicious. I have never made sourdough before but after seeing the picture of the loafs, I will have to give it a try.

    As always;

    Ad Astra Incrementis

  • Brad Neuberg December 24, 2010, 17:46

    Happy holidays to you too! I absolutely love this site; thanks for all the hard work!


  • Mark Wakely December 25, 2010, 14:12

    A few questions about the bread:

    1. How much per loaf? (You are willing to sell them, aren’t you? They look so good…)

    2. Do you ship for a flat rate?

    3. Have you thought about using the profits to help fund interstellar reasearch? If so, your new motto could be “To the stars…one loaf at a time.”

    All kidding aside, have a very Merry Christmas.


  • Josh Haigh December 25, 2010, 16:33

    Merry Christmas!
    Thanks for your continued work on this blog, it is much appreciated.

  • Paul Gilster December 25, 2010, 17:39

    “To the stars…one loaf at a time.” Love it!

    Thanks to Mark Wakely for the bread idea, and to all of you for your good thoughts. Much appreciated!

  • David December 26, 2010, 2:37

    Merry Christmas to Everyone. May it be great year for all.
    Paul, thanks for a great blog.


  • Paul Hughes December 26, 2010, 4:41

    I must say that baked bread looks absolutely delicious. :) A happy holiday season to you too Paul!

    It is encouraging how successful they are finding these NEA’s, not only for an impact early warning system, but for their usefulness in future space settlements. Imagine the day when there are no more NEA’s, as they have all been utilized for space settlements and ships to the stars.

  • Greg December 27, 2010, 11:13

    Merry Christmas to Paul and Marc and their avid readers! I can’t say how much I enjoy such excellent scientific journalism and thought provoking articles. I look forward to seeing what the New Year brings!