BREAKING: Sofa-sized asteroid gives us a close shave

By Phil Plait | February 4, 2011 12:21 pm

As I write this, in less than a half hour (at 19:40 UT) an asteroid 1-2 meters in size will pass about 12,000 5500 km from the Earth’s surface: less than 7500 3500 miles! The Earth itself is 13,000 km across, so this is a close shave indeed. [UPDATE: Turns out the miss distance of 12,000 km was measured from the Earth’s center. Subtracting our radius of about 6400 km, the rock actually came about 5500 km from our surface — so, even closer than I originally thought. Sorry about the error, and thanks to Emily at The Planetary Society Blog where I saw the actual number.]

Still, it will miss, and would not be dangerous even if it did hit us. Got that? Cool.

This rock, officially named 2011 CQ1, was discovered just last night! Here’s a shot of it taken using a small 0.35 meter (14″) telescope at the Tzec Maun Observatory in New Mexico:

This is a combination of 20 short exposures tracking the asteroid; the stars appear as dotted lines while the asteroid itself as the indicated dot.

Now let me be clear: this rock will miss us, and even if it had been aimed at us it would be unlikely in the extreme to do any damage. It’s way too small. Most likely were something like this to hit us, it would explode very high in the Earth’s atmosphere, releasing as much energy as perhaps a ton or so of TNT. That may sound like a lot, but it’s actually not a big deal. Some estimates have us getting hit by meter-size rocks once per month or so. The fact that you never hear about them indicates they are no danger!

It would take something far bigger to hurt us. The rock that blew up over Tunguska in 1908 was probably 30 meters or so in size; that detonated with a yield of about 15 – 20 megatons of TNT, equivalent to a pretty big nuke (though without radiation). Something metallic that size would probably hit the ground intact, leaving a hole like Arizona’s Meteor Crater, which is over a kilometer across. Happily, impacts like that are extremely rare!

Smaller ones are more common. In late 2008, a smallish rock about the same size as 2011 CQ1 came in over the Sudan and exploded, raining down small rocks which were later recovered. No one was hurt.

So the point here is that CQ1 is too small to hurt us even if it were to hit, which it won’t. And the cool thing is that it was seen at all! Two meters is dinky indeed, and this kind of discovery, far from being scary, makes me happy because it means we’re getting better all the time at detecting rocks that might actually hit and do damage.

Image credit: Giovanni Sostero & Ernesto Guido. Tip o’ the Whipple Shield to reddit.

MORE ABOUT: 2011 CQ1, asteroid, impact

Comments (40)

  1. D Paul

    Are we sure someone from the ISS isn’t just chucking rocks at us?

  2. Very cool! Although it is a LITTLE disconcerting that they just discovered it last night and it’s going to pass so close! Another hint that we need to make sure we keep on funding those NEO tracking programs….

  3. But what if it DOES???

    Oh, wait, it’s not 2012 yet…

  4. Elwood Herring

    How much will it miss us by?

    Off-topic – what’s all this about a UFO over Jerusalem? I’ve seen the videos and I’m not convinced.

  5. The moon-Earth barycenter orbits the sun at average 29.78 km/s, obviously slightly faster in February. 2011 CQ1 missed a hit by somewhat less than 6.7 minutes. No problem… if NASA respects the sign of the miss. NASA has had some interesting results mixing units and confabulating fore and aft.

  6. MarkW

    @Elwood Herring #3: obvious CGI fake is obvious.

  7. So, just for fun, is there any way to calculate the location on Earth that it passed closest to?

  8. Dang! I could have used a new sofa.

  9. Rob Matson

    What’s particularly interesting about the path of 2011 CQ1 is that it will transit the sun as seen from a narrow swath across the Pacific Ocean, Chile, Argentina and the south Atlantic. Unfortunately, the transit path is south of all the big observatories in Chile, and the asteroid itself will only subtend at most a couple tenths of an arcsecond. Buenos Aires and Montevideo are on the transit path. Bill Gray has (very rapidly!) put together a transit map for South America at this link:

  10. Martha

    I think a reading of the Mayan Calender will show that the arrival of a sofa from Nibiru was predicted to happen as a precursor to 2012.

  11. AliCali

    Sofa-sized, eh? If it was also sofa-shaped, maybe it fell out of the alternative Millennium Falcon (from Family Guy)?

  12. You said sofa, and I instantly thought of the Hitchhiker’s Guide to the Galaxy. You sure that’s not Arthur Dent chucked out a Vogon airlock? I’m sure Ford knows exactly how he feels.

    Or is that a Chesterfield sofa?

  13. Levi in NY

    I would *love* to see the fireball from something like that exploding in the upper atmosphere!

  14. Number 6

    After reading the comments….I’m confused….Is it a comfort that it’s sofa-sized or a sofa that just whistled by us? I guess we’ll be able to verify this based upon whether small, interstellar rocks rain down or whether moldy, Cheetos, loose change, and a missing universal remote pelt the earth.

  15. Joseph G

    Was it the size of a king-sized sofa? Was it sofa king close? :)

  16. Larian @12, I was also wondering if this might be a velvet paisley-covered Chesterfied.

    Arthur looked. Much to his surprise, there was a velvet paisley-covered Chesterfield sofa in the field in front of them. He boggled intelligently at it. Shrewd questions sprang into his mind.

    “Why,” he said, “is there a sofa in that field?”

    “I told you!” shouted Ford, leaping to his feet. “Eddies in the space-time continuum!”

    “And this is his sofa, is it?” asked Arthur, struggling to his feet and, he hoped, though not very optimistically, to his senses.

    – Douglas Adams, “Life, the Universe, and Everything”

  17. Andrew W

    “Most likely were something like this to hit us, it would explode very high in the Earth’s atmosphere, releasing as much energy as perhaps a ton or so of TNT. ”

    More like a hundred tons of TNT. (yep, I’m being pedantic!)

  18. Magrathea

    @Larian LeQuella: do you know where your towel is?

    @Levi in NY you’d be disappointed I imagine unless it was made of more metals and made it in the lower atmosphere 😉

  19. Robert S-R

    @J Major: If it was larger, we probably would have seen it earlier, and if it were going to hit, and do damage, it would certainly be large enough to see from further away. Rocks this size come close (and hit) all the time; they’re hardly a priority from a national security standpoint. The ones to watch out for are being watched out for, and I believe most of them are accounted for.

    Right, Phil? We know where all the bigger-than-a-sofa-sized ones are, right? Oh god oh god oh god…

  20. Pete Jackson

    Phil, you must have been tired when you wrote this. If you had been hungry, you would have called it the size of a refrigerator; if you were ready to go somewhere, you would have called it the size of a motorcycle…

  21. #9 Hey, just over my head!

  22. BreadFred

    I wasn’t aware of this measure of mass. But I approve :)

  23. KEA

    And where was our trillion dollar defense department? …can’t it defend us against anything?

  24. Bill

    @Rob (#9)

    > Bill Gray has (very rapidly!) put together a transit map for South America…

    And I bet Thierry Legault got there in time to get a stunning shot of the silly thing transiting the sun.


  25. reidh

    How big to hurt us, how too small to detect, does one have to be?

  26. reidh

    How big does one have to be to hurt us, and how small to be undetectable till its too late, does one of those puppies have to be? like whats the threat range?

  27. Thameron

    It missed us? Well so-fa so good then. It must have missed because it was so-fa away, or perhaps I should couch that in other terms. Hmmm.

  28. Hammill

    Incredibly cool!

  29. JupiterIsBig

    12 & 16 – I too thought that Eddie must be around.

    An update is that is was 5480km from earth and it’s orbit was changed by 60 degrees !
    I read this via Spaceweather

  30. Aaron

    Even if we were able to detect it, we surely wouldn’t be able to deflect it, for everyone knows that you can’t hit a target that’s only two meters wide!

  31. OT

    Phil, I know you can help me. I just shared the latest pictures of the Apollo 14 landing site from LRO. and my friend commented on my post – saying the footprints were sure to become some of humanity’s most enduring artifacts as they were still looking crisp after 40 years.

    Well, of course they do, because without an atmosphere on the moon to erode them they will last… how long? I googled, and to my dismay found that the time estimates vary from just 100 years (mentioned on the bad astronomy forum) up to “millions of years.” “A very long time” seems to mean something different to everyone.

    I will trust your answer. How long will our astronaut’s footprints remain on the moon?

  32. Joseph G

    @31 Aaron: I used to bullseye womp rats in my T-16 back home; they’re not much bigger than two meters.

    Ah, those were fun times! Flying around with my friends, blasting furry animals. Until my parents found out… To hear them tell it, you’d think I went all Sith on them. They took my damn T-16 and made me go to counseling. Sheesh. Overreact much?

  33. Michel

    Near misses are sooooo 2011.

  34. Messier Tidy Upper

    @ Joseph G : LOL. 😉

    @27. Thameron : Ditto LOL. :-)

    Sitting on the sofa
    Watching asteroids go past
    The Earth is in the firing line
    But this is just a blast! :-)

  35. Gary Ansorge

    Ah, the panic of the masses. In todays Independent, there was this jewel; “Just discovered asteroid over a mile in diameter may impact in 2019,,,”.

    They then blew their story by naming the asteroid(2002 NT7), which says it was discovered in 2002. Nine years ago is hardly what I would call “newly discovered”.

    News media should NOT try to be profit centers. That just reduces them to breathless rumor mongerers, getting people all excited about,,,absolutely nothing.

    Gary 7

  36. Brian Too

    I dub thee a sofaroid!

  37. Sam H

    In September 2008 an asteroid estimated to be about the size of an office desk impacted somewhere in Saskatchewan (the pieces weren’t recovered until much later). I didn’t see it :(, but the videos and eyewitnesses showed the midnight sky lighting up like sunrise happening early over my home province of Alberta. I remember begging my Dad to take me out asteroid hunting in another province!! As for the rock itself, looking back now there were some bigger-than-expected pieces recovered, so it should have been semi-metallic and probably made quite a crater. Imagine what it would be like standing, say, 10 kilometres or so from the impact!! 😮 It’d be the most incredible thing you’d ever hear (and probably the last).

    If I ever do get my hands on an asteroid piece I’ll make a necklace or ornament out of it, then sell the rest.


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