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Introducing Asteroid 2004 MN4 633

Numerous readers wrote in with bits about a potential asteroid collision: "The recently discovered asteroid 2004 MN4 is currently listed as having a 1/233 chance of hitting the Earth. It is 420 m across and if it strikes the Earth it will release an energy of 1,900 Megatons of TNT (the largest nuclear weapon ever detonated, Tsar Bomba had a yield of only 50 Megatons). It is also the only asteroid that currently has a Torino scale value of 2." So, in summary, there's a 1-in-233 chance of the worst disaster in recorded history happening on April 13, 2029, and a 232-in-233 chance of nothing happening. Have a nice day! Update: 12/24 22:14 GMT by M : The rock is now rated a 4 on the Torino scale, or a 1-in-62 chance of impact.
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Introducing Asteroid 2004 MN4

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  • by Anonymous Coward on Friday December 24, 2004 @01:44PM (#11177131)
    Dude, we're like living on a sphere...
  • by LnxAddct ( 679316 ) <sgk25@drexel.edu> on Friday December 24, 2004 @02:08PM (#11177280)
    I think what he was getting at was that its already been determined if we'll be hit, we just don't know and can't know the answer yet. We can only judge it to a certain accuracy, giving us a certain probability. In reality though there is a definite answer that we just don't know. However, the grandparent is wrong in that when you get to the quantum level, things really are impossible to figure oout.
  • by Phrogman ( 80473 ) on Friday December 24, 2004 @02:16PM (#11177322) Homepage
    Oh thats great fun. I calculated the results for a 1320m asteriod made of dense rock arriving at 17m/s on a 45 degree angle and impacting on land for someone standing 100km (62.5 miles) away:

    Your Inputs:
    Distance from Impact: 100.00 km = 62.10 miles
    Projectile Diameter: 1320.00 m = 4329.60 ft = 0.82 miles
    Projectile Density: 3000 kg/m3
    Impact Velocity: 17.00 km/s = 10.56 miles/s
    Impact Angle: 45 degrees
    Target Density: 2500 kg/m3
    Target Type: Sedimentary Rock

    Energy before atmospheric entry: 5.22 x 1020 Joules = 1.25 x 105 MegaTons TNT
    The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 9.2 x 105years

    Major Global Changes:
    The Earth is not strongly disturbed by the impact and loses negligible mass.
    The impact does not make a noticeable change in the Earth's rotation period or the tilt of its axis.
    The impact does not shift the Earth's orbit noticeably.

    Crater Dimensions:
    What does this mean?

    Transient Crater Diameter: 13.1 km = 8.12 miles
    Transient Crater Depth: 4.63 km = 2.87 miles

    Final Crater Diameter: 18.4 km = 11.4 miles
    Final Crater Depth: 0.711 km = 0.441 miles

    The crater formed is a complex crater.
    The volume of the target melted or vaporized is 3.22 km3 = 0.772 miles3
    Roughly half the melt remains in the crater , where its average thickness is 24 meters = 78.6 feet

    Thermal Radiation:
    What does this mean?

    Time for maximum radiation: 0.95 seconds after impact

    Visible fireball radius: 15.2 km = 9.45 miles
    The fireball appears 34.6 times larger than the sun
    Thermal Exposure: 2.29 x 106 Joules/m2
    Duration of Irradiation: 20.8 seconds
    Radiant flux (relative to the sun): 110

    Effects of Thermal Radiation:

    Much of the body suffers second degree burns

    Deciduous trees ignite

    Seismic Effects:
    What does this mean?

    The major seismic shaking will arrive at approximately 20 seconds.
    Richter Scale Magnitude: 8.0
    Mercalli Scale Intensity at a distance of 100 km:

    VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken.

    VIII. Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned.

    What does this mean?

    The ejecta will arrive approximately 144 seconds after the impact.
    Average Ejecta Thickness: 26.1 cm = 10.3 inches
    Mean Fragment Diameter: 11.8 cm = 4.65 inches

    Air Blast:
    What does this mean?

    The air blast will arrive at approximately 303 seconds.
    Peak Overpressure: 157000 Pa = 1.57 bars = 22.3 psi
    Max wind velocity: 242 m/s = 540 mph
    Sound Intensity: 104 dB (May cause ear pain)
    Damage Description:

    Multistory wall-bearing buildings will collapse.

    Wood frame buildings will almost completely collapse.

    Highway truss bridges will collapse.

    Glass windows will shatter.

    Up to 90 percent of trees blown down; remainder stripped of branches and leaves.
  • Re:The problem (Score:3, Informative)

    by Vaevictis666 ( 680137 ) on Friday December 24, 2004 @02:23PM (#11177352)
    Bah, given that they are independant, and each has a 232/233 chance of missing earth, that gives a (232/233)^233 or 36.7% chance of all of them missing.
  • Re:Ever Wonder... (Score:1, Informative)

    by Anonymous Coward on Friday December 24, 2004 @02:28PM (#11177371)
    Here is a link to a large amount of orbital data for this asteroid, which may be what you are looking for:

    http://newton.dm.unipi.it/cgi-bin/neodys/neoibo? ob jects:2004MN4;main
  • by ajs ( 35943 ) <ajs.ajs@com> on Friday December 24, 2004 @02:53PM (#11177552) Homepage Journal
    Even though 30 years is a drop in the universe's bucket in terms of time, there is a lot that could possibly alter the course.

    Other than human interference? No, not really. The chances of its running into some other body are probably far less than its running into the earth, and it's not like there's a lot of commuter traffic to get in the way. Space is rather empty -- pardon the cliché.
  • by maxverb ( 843284 ) on Friday December 24, 2004 @03:05PM (#11177610) Journal
    NeoDys is running a page on this asteroid, and at present they have raised the odds to 1 in 60, with a Torino scale value of 4 (not 2). Obviously they are refining the orbit as they get more data, so the value may change again. But, since I first saw this story, the odds have been 1/300, then 1/233, then 1/125, and now 1/60. Hmmm. This isn't on the news anywhere else yet, as fas as I can tell. Here's the link: http://newton.dm.unipi.it/cgi-bin/neodys/neoibo?ri skpage:0;main
  • by mc6809e ( 214243 ) on Friday December 24, 2004 @03:16PM (#11177672)
    Am I seeing this [nasa.gov] right?

    It looks like it's up to a 4, now.
  • Re:Ever Wonder... (Score:5, Informative)

    by Jerf ( 17166 ) on Friday December 24, 2004 @03:18PM (#11177676) Journal
    I guess I'd just like to see the math on how they come up with these numbers.

    Nobody's stopping you; it's not a secret. Go get it.

    But get ready for some heavy lifting; as you dig into it you'll very quickly realize why they didn't try to put any in a popular news article.

    I'm not too up on it myself but you can start with phase spaces [wolfram.com], I think, though that hardly touches the real fun, which is the probabilistic aspect of determining the path of an object through all of the influences of the solar system... while I'm not up on the details I do know they don't use naive formulations of that problem, they've got some powerful and brain-bending tricks to prevent the estimate from diffusing too quickly.
  • by Anonymous Coward on Friday December 24, 2004 @03:18PM (#11177678)
    >For example, we predict the trajectories of space probes through space decades in advance with very tiny margins of error.

    It's a good question. The answer is that space probes have radios mounted on them which broadcast at *very* precise frequencies. When receiving the probe's telemetry one can watch the frequecncy of the carrier wave. Any difference between the designed frequency and the actual frequency is a measure of the probe's velocity difference with respect to Earth. Factor out the Earth's motion and a few other well known factors, and you get an astonishingly precise velocity value. A photograph gives poor X and Y resolution, measuring Dopler shift gives excellent delta-Z resolution.

    Sadly asteroids lack tuned transitters.

  • by droleary ( 47999 ) on Friday December 24, 2004 @03:47PM (#11177838) Homepage

    We are clearly capable of tracking things through space with very, very low margins of error.

    To know where something is now doesn't mean you can predict where it will be in the future. Not within a "space is big" margin of error.

    So what's the bottleneck here?

    The very thing that makes it want to hit us: gravity. That is, the Three-Body Problem [wolfram.com], an 3 is at the lower end of influences that come into play over the next 25 years.

  • by japaget ( 836976 ) on Friday December 24, 2004 @03:50PM (#11177859)
    Yes, you are. It has been updated to include observations made through last night at 8:55 pm EST, 5:55 pm PST. And the impact probability has gone up to 1 in 62.
  • by at_18 ( 224304 ) on Friday December 24, 2004 @04:02PM (#11177916) Journal
    So what's the bottleneck here? Poor imaging?

    Yes. The image on the telescope is not a theoretical point, but has a certain diameter depending on the telescope diameter, atmospheric distortion, ccd resolution, etc. So you cannot pinpoint the asteroid position precisely, but only give a bounding box.

    Combining multiple observations will give you more data, and you can start narrowing down the estimate. Right now the error on the position, projected to year 2029, is about 200 times bigger than the diameter of Earth, so we say that there's a 1/200 probability of impact. A planet is a very tiny target.

    When the precision is sufficient to say that, for example, the asteroid will pass by the left side, it will suddenly drop to zero. If it is actually going to impact the Earth, the probability will slowly going up until it will reach 1.

  • by frakir ( 760204 ) <ockhamrazor@yahLIONoo.com minus cat> on Friday December 24, 2004 @04:09PM (#11177949)
    Even shape of that thing can influence its trajectory because it may reflect less light on one side then on the other... and those tiny forces add up over 20+ years.

    There are so many factors we don't know after 2-3 sightings of such a meteor to make more accurate prediction.
  • torino is now at 4 (Score:3, Informative)

    by Johnny Mnemonic ( 176043 ) <mdinsmore AT gmail DOT com> on Friday December 24, 2004 @04:12PM (#11177965) Homepage Journal
    The Torino scale for this impact is now rated [nasa.gov] as a "4"--about 1% chance of hitting us, an upgrade from previous estimations. Still not likely, but now more likely.
  • by Anonymous Coward on Friday December 24, 2004 @05:04PM (#11178178)
    This simply means that the "cloud" of possible trajectory intersections mentioned in the article has shrunk due to new data, and that the Earth is still inside this cloud. When the cloud is shrunk further by future observations, we might suddenly find ourselves outside it.

    So, I would not start planning the apocalypse party just yet. :-) It's one to watch for sure though.
  • Re:In numerology... (Score:5, Informative)

    by dos equis ( 21086 ) on Friday December 24, 2004 @10:39PM (#11179401) Homepage
    Not so fast!

    The number 4 in Japanese is "shi" (U+56DB), but "shi" also means death (U+6B7B)!
    It's just as unlucky as 13 in western culture, and more specific about our fate.
  • Re:Maybe (Score:2, Informative)

    by jonadab ( 583620 ) on Sunday December 26, 2004 @09:26AM (#11184493) Homepage Journal
    > All this 'If you break it up, it doesn't help' is just nonsense. Especially
    > with a rock this size, which is about enough to flatten a fairly large city,
    > if I'm understanding this correctly. If it's going to hit, we probably won't
    > learn where exactly until the last approach, at which point it's too late
    > to evacuate Calcutta or wherever.

    If it's large enough to flatten a large city, you don't want it to hit
    anywhere, not even in the middle of the Pacific.

    However, 25 years is a long time; we can afford to just *watch* it for fifteen
    years, and that still leaves ten years more, *plenty* of time to alter its
    orbit if necessary so that it doesn't hit. (All this malarke about blowing
    it to pieces with nukes is just so much movie-plot nonsense. It would be much
    easier and safer to mount a few rockets on it and push it off course so it
    misses. Especially if we have several years to work out the details.)

    Honestly, something that we see coming 25 years ahead of time isn't going
    to be scary unless it's *entirely* too large to move (i.e., sized more like
    a small planet than an asteroid), which seems unlikely -- and this little
    bitty thing isn't even close to that category. If you want to get yourself
    all worked up over the possibility of a large asteroid plowing into the
    Earth, think about one coming from a strange angle far out of the plane of
    the eccliptic so that we don't notice it until a few hours before it hits.

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