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Space Earth NASA Science

Large-ish Meteor Hits Earth... But No One Notices (discovery.com) 99

According to data released by the Fireball and Bolide Reports page of NASA's Near Earth Object Program, a large meteor exploded far off the coast of Brazil on February 6, 2016. The meteor was the largest atmospheric impact recorded since the famous Chelyabinsk bolide that exploded over Russia in 2013. Although the Feb 6 meteor didn't cause any structural damage, the meteor unleashed an energy equivalent of 13,000 tons of TNT exploding instantaneously.
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Large-ish Meteor Hits Earth... But No One Notices

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  • by bobbied ( 2522392 ) on Tuesday February 23, 2016 @07:03PM (#51570985)

    Whoosh!

  • by istartedi ( 132515 ) on Tuesday February 23, 2016 @07:07PM (#51571025) Journal

    Back in the 80s, I seem to recall wire services carrying reports of a "mushroom cloud" over the ocean. It was reported by commercial pilots, probably reliable witnesses not inclined to make up things for jokes.

    Speculation was undersea volcano, unusual thunderstorm convection, and impact. I don't recall them following up on it, and I think it remained a mystery... let's see if I can track this down in a few minutes before hitting submit....

    Oh wow, it was easier than I thought it would be. Here's the original story. [google.com]

    It was the 3rd google hit for "pilots spot mushroom cloud". Would that all my searches were that easy.

  • by Anonymous Coward

    East of Java by some 23000 mi. back in the late 1800s. No one noticed that was caused by a falling rock, hurled by the FURRY OF GOD!

  • Someone noticed (Score:5, Insightful)

    by Nkwe ( 604125 ) on Tuesday February 23, 2016 @07:12PM (#51571053)
    Someone noticed, or we would be reading about it here...
    • by Nkwe ( 604125 )
      ugh "wouldn't", as in "wouldn't it be nice if we could edit a post within a short period of time after posting".
  • out of the entire invasion force.
  • by rahvin112 ( 446269 ) on Tuesday February 23, 2016 @08:03PM (#51571327)

    When the planet's surface is 60% water the meteors are going to hit water 60% of the time. As a practical point of view most of the planet is devoid of human life when you take into account the areas like Siberia, the deserts and all the water, that the odds of an meteor hitting a populated area is staggeringly unlikely.

    • I'm pretty sure if the meteor were to crash in US you'd have systems and radars to at least track it for a bit, and know where it landed. You might even have StA missiles capable of locking in to the heat signature and exploding it (are they fast enough?). Not that I know if thats a good idea honestly but the technology should be there, right? This for your scenario of a rock like this hitting a city like NY where it makes sense to invest in it.
      • by rahvin112 ( 446269 ) on Tuesday February 23, 2016 @09:17PM (#51571881)

        The meteor would need to be at least the size of a fighter jet to be trackable. Beyond a certain size it won't even register on the radar because if radar tracked everything down to the size of small finch it would be overwhelmed by positive signals. A large meteor would almost certainly hit the tracking radar but the objects are moving so fast that by the time they notified anyone it would be over. But most meteors are of the size that they won't even register. The main point of my post is that most meteors don't hit near populated areas, as a percentage of the earth surface the entire USA doesn't even register beyond a single digit percentage making a rare event even rarer.

        • by afidel ( 530433 ) on Tuesday February 23, 2016 @09:39PM (#51572043)

          According to this article [newgeography.com] 2.7% of the land area is urban, that means ~1% of the total earths surface is urban land. If strikes are completely random then there should be a 1% chance that any given hit is in an urban area. Now I don't believe hits are completely random since the solar system is planer so areas nearer the equator probably have a higher percentage chance, but that may be balanced by more cities being near the equator (there are almost no large cities between 60 degrees north and 90 degrees and in the southern hemisphere it's even more striking with no large cities between 45 degrees south and 90 degrees)

          • the solar system is planer so areas nearer the equator probably have a higher percentage chance,

            True.

            but that may be balanced by more cities being near the equator

            False.

            (there are almost no large cities between 60 degrees north and 90 degrees and in the southern hemisphere it's even more striking with no large cities between 45 degrees south and 90 degrees)

            True - for a final score of 66.7%.

        • by tnk1 ( 899206 ) on Tuesday February 23, 2016 @09:58PM (#51572143)

          Yes, this was incidentally why ballistic missiles launched from subs off the coast of the US were a huge concern. By the time you knew they were coming, you had about ten minutes or less to react. And there wasn't really anything short of other nuclear missiles that could shoot down an ballistic missile until recently, and nothing that could probably be activated on that sort of a notice even now.

          A meteor would probably come in as fast as a ballistic missile, and we wouldn't even have the advantage of knowing where the launch sites are and monitoring them.

          The big advantage over ICBMs is that they generally come from farther away and so there is more time to see them coming, but that assumes that you get lucky and find it before it enters the atmosphere. If you didn't see it coming, there's going to be zero chance of tracking it long enough to do anything about it, if you even saw it coming. At that point, even if you hit it with something, unless you atomized it the debris are going to impact and do a similar amount of damage.

        • Radar primarily distinguishes by speed, not size. Objects below a speed threshold are ignored (*). Radar systems usually don't know much about the target's size, all they have is the strength of the return signal which depends on the radar cross section (i.e. reflectivity) of the target. The same object can have hugely different RCS, depending on the angle at which you're looking at the object.

          *: this was a big problem in the development of the AEW radar system for the Hawker Siddeley Nimrod: the RAF had sp

          • "this was a big problem in the development of the AEW radar system for the Hawker Siddeley Nimrod"

            It might have been a problem in the early days, but by 1995 the systems onboard were good enough to notice and zoom in on a single bouy in the middle of the irish sea from 100 miles away ("show me everything that doesn't look like water" - which had enormous implications for SAR work) by 2005 they were boasting the Nimrod's systems could track people walking in Afghanistan

            Helicoptors should be relatively easy a

            • I was talking about the Nimrod AEW.3 project which was abandoned in 1986 because they couldn't get the radar to work.
              You're talking about the Searchwater radar (and possibly other sensors like the IRST) on the MR2 version.

        • by dcw3 ( 649211 )

          From Wikipedia: some modern systems use shorter wavelengths (a few centimeters or less) that can image objects as small as a loaf of bread.

          And no, they would not be "overwhelmed by positive signals" either.

        • by TheSync ( 5291 )

          The meteor would need to be at least the size of a fighter jet to be trackable.

          Meteors leave long trails of ionized gas that are reflective to radar. Here is a radar meteor trail [wisc.edu].

    • When the planet's surface is 60% water the meteors are going to hit water 60% of the time. As a practical point of view most of the planet is devoid of human life when you take into account the areas like Siberia, the deserts and all the water, that the odds of an meteor hitting a populated area is staggeringly unlikely.

      Less and less staggering all the time... especially on the central Florida peninsula, NorthEast urban corridor, Western Europe, etc.

    • > When the planet's surface is 60% water the meteors are going to hit water 60% of the time.

      Not [harvard.edu] exactly true [harvard.edu]. There seems to be a relationship between the fall rate and latitude.

      Also, the northern hemisphere has proportionally more land than the southern hemisphere [stackexchange.com] (68% vs 32%), you'd expect about twice as many NH impacts on land than in the SH.

  • by Anonymous Coward

    Has Fox blamed it on Obama yet?

  • If it takes military technology to hear a 13 kiloton meteor go off in the ocean, then we have finally found what we need to hear a tree fall in the forest.
  • ..and no one heard it, did it make a noise?
  • Hits earth means it touches the water or land. Atmospheric burn up is NOT a "hit".

    • by fisted ( 2295862 )

      Yes it is. Why would only solids and liquids qualify as Earth? And if the atmosphere is not part of Earth, then part of what is it?

    • That's why it is called a meteor and not a meteorite.

  • it fell in the Atlantic close to Brazil. Now, imagine if it had exploded on the water and caused a tsunami. Brazil was in the middle of Carnaval, where most people go for the coast to celebrate. That would be devastating.

  • Nobody was looking (Score:2, Informative)

    by Anonymous Coward

    Since the Spanish Meteor Network [spmn.uji.es] started to work full steam, each month or so there have been reports in the news of large fireballs brigtening the night sky over the Iberian peninsula [wikipedia.org]. And every few years about really big superbolide ones.

    Even when every station is able to detect them only up to 500km away at best. the network reports 500 bolides [spmn.uji.es] every year, the lastest one this same week [youtu.be]

    The sky is falling, but nobody is looking.

  • the meteor unleashed an energy equivalent of 13,000 tons of TNT exploding instantaneously.

    As opposed to the other kind of TNT explosion that takes aaaaages.

    • by jabuzz ( 182671 )

      Well TNT does not explode instantaneously and 13,000 tons of the stuff is sufficiently large (roughly a 20m cube if my maths is correct and we are assuming liquid TNT with density 1.65g/cm^3) that there would be a roughly 0.003 second delay for the shockwave to propagate though (detonation speed for TNT is 6900m/s) it and set it all off if there was only a single detonation point.

      • Try computing that using Octol. That's the same explosive they used at one point to set off nuclear weapons before they shifted to another composition to reduce cost.

  • I mean, the one that nearly trashed Chelyabinsk was the most recorded bolide to date, but this one was in the middle of the South Atlantic.

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