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Record-setting “near miss” of Earth dramatically shifted tiny asteroid’s orbit

The views expressed are those of the author and are not necessarily those of Scientific American.


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Orbital diagram of asteroid 2011 CQ1 and its flyby of EarthThe solar system is littered with natural debris—asteroids, comets and pieces of the same that occasionally wind up in the steamrolling path of one of the planets. When a piece of debris encounters the friction of Earth’s atmosphere, it flares up as a meteor, or shooting star, and pieces of the object may survive the heat of reentry to reach the surface as meteorites.

Many more objects whiz past Earth without striking the atmosphere, perhaps returning for another pass some years later. Many of those go undetected, especially the small asteroids that are harder to spot with the relatively modest telescopes that keep watch for near-Earth objects.

But sky monitors did spot one small asteroid, called 2011 CQ1, less than a day before it buzzed Earth at the smallest distance ever recorded. On February 4, the meter-size rock flew over the Pacific at an altitude of about 5,500 kilometers—about one-seventieth the distance between Earth and the moon and well below the orbit of some high-flying satellites.

But even though 2011 CQ1 skirted immolation in Earth’s atmosphere, it did not escape from the encounter unmolested. Earth’s gravity gave the asteroid a good tweak, redirecting its trajectory by about 60 degrees in much the same way that interplanetary spacecraft use the gravity of the planets for course corrections or speed adjustments. "Prior to the Earth close approach, this object was in a so-called Apollo-class orbit that was mostly outside the Earth’s orbit," asteroid trackers Don Yeomans and Paul Chodas wrote on the NASA Near-Earth Object Program Web site. "Following the close approach, the Earth’s gravitational attraction modified the object’s orbit to an Aten-class orbit where the asteroid spends almost all of its time inside the Earth’s orbit."

Just what is in store for the tiny asteroid is unclear—faint as 2011 CQ1 is, it was visible only briefly, when it was very close to Earth, and its newly adjusted orbit is not well understood.

Orbital diagram of 2011 CQ1′s encounter with Earth: NASA





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  1. 1. RAshbyF 8:21 pm 02/10/2011

    I may be missing a point here, but wasn’t "The Great Daylight 1972 Fireball" <http://en.wikipedia.org/wiki/The_Great_Daylight_1972_Fireball&gt; a closer near miss? From what I can gather, it was larger and more massive, so if one qualifies as an asteroid, so does the other. But maybe the "record" only refers to objects which were discovered before closest approach?

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  2. 2. jtdwyer 9:24 pm 02/10/2011

    Astronomers seem to be all about seemingly arbitrary classifications, specifically from an observer’s officially standardized perspective, which led to the great Pluto debate and, IMO, the perception of an accelerating universe, but I think the author effectively said: asteroids & stuff in interplanetary space; satellites orbiting the Earth; meteors entering the Earth’s atmosphere; meteorites striking the Earth’s surface. I think a near miss might be one of those non-orbiting objects that do not enter the atmosphere or make material contact?

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  3. 3. focalist 8:52 am 02/11/2011

    I do believe you are correct.. and I always found those definitions to be awfully vague.. but there you go. In any case, I always found myself "torn".. as an inquisitive type, I’ve always had the morbid desire to see (if only from TV) a modern planetary impact here on Earth, and have it be well-observed, scientifically.

    I say morbid because the energy delivered by even a small impactor is incredible as I understand.. I’m of the group that believes Tunguska (?sp) in the early 20th century was a small to mid size impactor, possibly even a bolide that never even made it to the surface and functionally was an air-burst explosion of huge scale as the (non)impactor vaporized. In the case of Tunguska, it was in rural Russia, nearly unpopulated- but the damage extends to a huge area. Should something like that happen to a populated area, the casualties and destruction would be enormous. Nobody wants to see that.

    For the science, and the spectacle- maybe Sahara? Desert US? I’d prefer over land (prefer being loosely used).. but then you are almost guaranteeing human loss.

    Impacts happen all the time on a planetary time scale.. but I fear getting what I ask for might be more than I really want..

    By the way, curious.. what do you do for a living? You seem to have wide interests and are rather eloquent. Writer?

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  4. 4. jtdwyer 9:47 am 02/11/2011

    Thank you very much for you kind remarks. I’m a retired information systems analyst type with a broad very technical but also financial background. For many years I determined equipment configuration requirements for perhaps the largest and fastest growing commercial computer center and wrote the capital requests for funding. After those many years as a workaholic, health issues limit my physical activities – so I spend much of my now extensive spare time characteristically analyzing scientific information. While certainly not a qualified scientist, I am a successful problem solver who apparently brings something completely different to the table. Enough self-aggrandizement – I’m actually just some old guy now.

    I once saw one of those larger meteors burn out in the atmosphere, sporting a tail of glowing embers, at least for a few seconds, while driving on a long trip. Quite impressive. I also recall, as a preschooler, laying across the back shelf under the rear window in my Dad’s ’53 Mercury as we drove across Texas, searching the incredibly star filled night sky for falling stars. On the other hand, following my time in Viet Nam I’ve never really liked even small explosions – I’ll pass on any observations of large impactors, thanks!

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  5. 5. focalist 10:11 am 02/11/2011

    Actually, ditto here. Programmer/engineer for many years, quite a varied history before that.. medical, special education teacher.. but got taken out of working world by Crohns and complications thereof. I spend a lot of time sick.. most of my time "here" is from where I spend a few hours a day- a 4×8 porcelian cell. Though it sounds like you have a decade or so on me (I was born during Vietnam, so there ya go)…

    Explosions for me are both terrifying and fascinating.. when I was 15, I survived but lost both my parents to a propane explosion in our home. I know far too much about the mechanics involved, for a time I became obsessed.. intellectualizing to cope and all that stuff. That being said, I really don’t think of an impactor in the same mental vein as that, somehow. It’s very odd WHICH perceptions are forever tweaked by things like that.. PTS is hard for those that don’t feel it now and then to uderstand. Even these days, I can always tell you the fastest exit from ANY building. It’s automatic for me, since that day. Odd, but understandable.

    I’ve always had a penchant for physics and simply enjoy understanding what makes this oddball rock tick. Sciam, though occasionally dropping the ball, has been a constant "high level" inroad to many subjects.. for decades in print, and now electronically.

    Nice to meet ya ;)

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  6. 6. jtdwyer 11:26 am 02/11/2011

    Pleased to meet you. Sorry life’s been so difficult for you – I’ve had some extended periods of extreme difficulty but have found a way out so far. The nearest I can relate to Crohn’s is an unusual condition: several years ago, over a period of a few days, my waist size increased by 4-5 inches, for no apparent reason. My abdomen seemed to be inflated to about 30 psi – it was really taut. I also noticed that my diaphragm would not extent into my abdominal cavity, severely restricting my breathing. Of course, eating anything aggravated my breathing problems, and I didn’t seem to be digesting anyway. Laying down to sleep I began coughing fluid out of my lungs. I literally couldn’t breath, eat or sleep.

    After seeing my GP, GI & cardiologists for three months of this, including a brief hospital stay in which I almost became violent (I later realized that I was having anxiety attacks as a result of my inability to breath, eat or sleep and the lack of assistance/aggravation I was getting from hospital staff), my third cardiologist put me on the standard medication for congestive heart failure (a beta-blocker). My symptoms were essentially relieved overnight! Within a couple of days my waste was even back to normal.

    To keep it short, CHF can cause the release of enormous amounts of adrenaline to compensate for ineffective heart function, but the heart can’t become more effective because it’s damages, already. Organs fail, cellular waste fluids build up, etc. The symptoms I had were really unusual – they used ultrasound to search for fluids inflating my abdomen but found very little. I think that the excess adrenaline was causing my digestive organs to physically ‘tighten up’, increasing their volume. But what do I know?

    Anyway, I hope you find this amusing – I can laugh about it now, anyway. Nowadays I’m taking the maximum does of beta-blockers twice daily (makes me sleep and/or be tired much of the time) and 8 other meds. Fortunately, the side effects are for now worse than the primary symptoms.

    While I can’t really comprehend your difficulties, I can empathize to some extent. Keep on hanging in there & continue to marvel at the universe! Don’t mind me if I sometimes become overbearing – I’m just an obsessive/compulsive problem solver…

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  7. 7. Postman1 9:17 pm 02/11/2011

    focalist- When you have time, check out universetoday.com . They have new articles daily, and I think you will enjoy them. Space.com has good reading too, but they rebuilt the site a few weeks ago and the comments section is now missing. Still good reading. Enjoy!

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