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Cosmic Shooting Gallery

(27 posts)

  1. Marian

    An meteor exploded today over a Russian city. Scientists simultaneously are saying this is not connected to the asteroid that's about to brush past the earth but that asteroids do travel in swarms. One used the phrase that the earth is in a cosmic shooting gallery. Something to think about as that implies there could be more over the next few days or weeks.

    Here is a video:

    It caused a staggering 900+ injuries. However, the injuries seemed to be caused by flying glass from shattered windows. That's something you don't see mentioned in meteor hits earth scenarios. And it's ironic in a way. Our advanced technology makes us more vulnerable, i.e. having glass windows, etc.

    Posted 7 years ago #
  2. geoffhart1962

    I've begun to wonder if we're not passing through an unusually debris-laden patch of space. Many of the near misses that have been reported (including an asteroid that will shortly pass *inside* the orbit of geostationary satellites; are things we notice only because we've started looking hard for such things.

    But still. There do seem to be an awful lot of them being announced lately. Perhaps it's time to dust off that parasol and start carrying it about with me when I'm outdoors, just in case. (Hey, it worked for Wile E. Coyote, didn't it? *G*)

    Posted 7 years ago #
  3. AKAkarlb

    Geoff: Yes, we are looking a lot harder these days. The whole effort is about only 30 years old and originally used only one telescope. Many more now in use, and they're much more sensitive. So I doubt we're passing through a particularly cluttered patch of space, particularly when you consider that almost all - maybe all - impactors are solar system objects, not interstellar interlopers.
    Marian: regarding the injuries you mention, I am reminded of the old "duck and cover" A-bomb protection drills of the 50s that were later so much maligned.
    If you're inside the radius of total destruction of a nuclear bomb the only thing to do is to assume the position: bend over, put your head between your legs, kiss your a** goodbye.
    But in the area of partial destruction, which a little geometry will demonstrate is far larger than that of total destruction, flying objects like glass shards are a huge danger. Duck and cover makes a lot of sense in that case. The people who advocated it weren't idiots.
    So if you see a large glowing object racing across the sky, duck under something and cover up your eyes.

    Posted 7 years ago #
  4. Greg

    Several additional videos of the Russian meteor explosion:

    The topmost 33 second clip shows how brilliant the flash was.

    Apart from the Alabama woman who was struck by a meteorite in 1954, I don't recall ever hearing about anyone who was injured.

    Posted 7 years ago #
  5. Marian

    Good point, Karl about duck and cover. I suspect most people saw the flash and ran to the window to see what was going on.
    It reminds me that my parents were awakened by an earthquake (Sylmar Quake around 1970) and stayed in bed. Later the family doctor mentioned that is the best thing to do as all the injuries he treated from the quake were glass cuts from people running barefoot to get outside.

    I wonder if anyone was actually struck by a meteorite fragment or if it is all broken glass. If so, then that Alabama woman is still the only human in history to have a direct hit from a meteorite.

    Posted 7 years ago #
  6. AKAkarlb

    GSH and Marian: there are LOTS of reports throughout history of people being struck and killed by meteorites, though in almost all cases the details are sketchy at best:

    I've read the book by John S. Lewis quoted in the text, though too long ago - 1996 - to recall much in the way of details. I do remember the case of the Franciscan friar in the 1600s - that's what I was googling when I found the above.

    And here's another report I hadn't heard about at all until today, of a supposed Tunguska-type event in Brazil in 1930:

    Most interesting, and so are the links at the end of the article.

    Finally, here's a good Slate article on what's been happening in the search for potentially dangerous NEOs and PHAs (Near Earth Objects and Potentially Hazardous Asteroids):

    And one on what they call the last time that Russia got wacked from space (they forgot the Sikhote-Alin strike in 1947):

    Sikhote-Alin itself:

    I'm just d*mn glad that none of these happened during the height of the Cold War, no telling what might have ensued.

    Posted 7 years ago #
  7. AKAkarlb

    BTW, the first serious speculation on what might happen if a giant meteor or asteroid hit the Earth appeared in Analog in 1966: J.E. Enever's article "Giant Meteor Impact":

    Posted 7 years ago #
  8. AKAkarlb

    Apparently at least one person remembered those old drils. From today's story in the NY Times about the meteor:

    "... a fourth-grade teacher in Chelyabinsk, Yulia Karbysheva, was being hailed as a hero for saving 44 children from glass cuts by ordering them to hide under their desks when she saw the flash. Having no idea what it was, she executed a duck-and-cover drill from the cold war era, with salutary results.

    Ms. Karbysheva, who remained standing, was seriously lacerated when glass severed a tendon in one of her arms, Interfax reported; not one of her students suffered a cut."

    Posted 7 years ago #
  9. Marian

    What a quick thinking teacher! How sad that she herself was injured. Proves your advice was right, Karl.

    Let's see now. Meteorite explodes above Russia and a few hours later an asteroid, as expected makes a very close pass. Then a fireball seen above San Francisco and today one above Florida. This certainly supports what that one astronomer said, that asteroids seem to travel in groups. We can hope to only have fireballs, which actually seems more likely.

    Posted 7 years ago #
  10. Marian

    Whew! We don't have to worry. Turns out it was just The Great Satan performing tests over Russia

    Posted 7 years ago #
  11. Greg

    Yeah, we've got a Secret Meteor Weapon. Our enemies had better back off, or we'll go all Ming the Merciless on them.

    Posted 7 years ago #
  12. David the Evil Overlord

    Unfortunately, my magnetic tractor beam only works on nickel-iron asteroids.

    One other minor bug in the system is having an asteroid land on top of the tractor beam. Oh, and on top of the minion who turned it on.

    Good tractor beams are expensive.

    Posted 7 years ago #
  13. Dr. Sardonicus

    The trajectory of the "near miss" asteroid seems to have been determined pretty nearly. However, news accounts haven't said much about the trajectory of the meteor that exploded over Russia. If the two objects were moving in very different orbits around Mr. Sun, that might discount the idea of their being part of a single "group" of objects better than the time difference, which was noted in some reports.

    I also didn't hear anything about the composition of the asteroid; I don't know whether anything is known about that. I seem to recall hearing the meteor (now meteorite) was rocky; so if the asteroid was nickel-iron, that too might indicate the two objects had different origins. There seems to be a mad scramble to get fragments of the meteorite.

    I seem to recall hearing that after the Boxing Day tsunami in 2004, one of our diplomats (possibly the Ambassador, but I don't remember) had to spend quite a bit of time trying to explain to the Turkish authorities that the earthquake and tsunami were NOT the result of a secret US hydrogen bomb test...

    Posted 7 years ago #
  14. AKAkarlb

    It was pretty definitely a coincidence. The trajectories were quite different and at the time of the asteroid pass-by the Earth - moving at 18.6 miles per second - was about a million miles from where it was at the time of the meteor explosion. See this for a more detailed explanation:

    It is not quite as big a coincidence as it first seems, however, because events like the Russian meteor actually are not that infrequent, for example:

    This happened over a sparsely populated area, it took a while for word to get out, it was about a tenth the size of the recent explosion, and Indonesians don't use dash-cams like Russians do so no pictures to catch the world's attention.

    The Defense Department (and, I suspect, its Russian counterpart) knew about this phenomenon for decades - it was picking up evidence of multi-kiloton blasts in the upper atmosphere through spy satellites designed to track nuclear
    explosions, but kept the info classified until after the end of the Cold War. I remember the stir it created in astronomical circles in the 90s when DOD declassified the evidence - nobody had known. Remember: most of these explosions happen over water and most are noticeably smaller than the Russki event and occur very high in the atmosphere, so they go unseen. click on the link in the story for a list of 27 such events that happened between 1994 and 2009.

    I think the Chelyabinsk meteor may well prove to be a game-changer in terms of awareness of impact dangers. Can't ignore this one.

    Posted 7 years ago #
  15. ByronBailey

    Rather than a shooting gallery, I prefer to view it more as a cosmic fireworks show. Just don't get too close or you'll get burned. Is that a stray bottle rocket comming our way? What a pretty, sparkly tail it has.

    Posted 7 years ago #
  16. Marian

    Final word on its composition, ordinary chrondite

    An industry selling fake fragments is growing explosively.

    Posted 7 years ago #
  17. robertbrown

    Marian wrote: "Our advanced technology makes us more vulnerable, i.e. having glass windows, etc."

    So you're saying those who live in glass buildings shouldn't throw stones.

    I agree with karlb, for sure: no one saw this coming, so it's clear we don;t know as much as we think we know about mountain-s ized debris packets swirling around us in NE space, just waiting to spiral down and plop ever so ungently onto...anything at all.

    Perhaps this event combined with the prospects of asteroid mining will get everyone on Earth together as a people, and stop thinking so small.

    But probably not.

    Posted 7 years ago #
  18. geoffhart1962

    In the category of "reassuring [not!]", a reminder that even if we're looking carefully, we might not see some asteroids in time to do anything other than yell "duck!":

    Posted 7 years ago #
  19. Marian

    Tomorrow, Saturday, another good sized one will do a harmless fly by. But while harmless, it was only noticed less than a week ago

    Are we having more of these or are simply detecting them where a few years ago these asteroids would have zipped by unnoticed.

    Posted 7 years ago #
  20. geoffhart1962

    Marian wondered: "Are we having more of these or are simply detecting them where a few years ago these asteroids would have zipped by unnoticed."

    Undoubtedly, we're seeing more because we're looking more. There's a direct causal link. Previously, we would only have noticed even large rocks by chance, if we happened to be looking at something else when the rock wandered across our field of view.

    As I noted earlier, it would be interesting to have someone knowledgable tell us whether there are also locally dense areas of debris that periodically orbit back into our sphere of influence. A large amount of the large spatial debris that could hit Earth has long since done so; 4.5 billion years is an awfully long time.

    But just as we have large annual meteor showers several times per year, I suspect there are also large debris clusters that only come within range of us over long periods due to things like precession of Earth's orbit around the Sun. These are the kinds of things that would occur over periods of thousands, tens of thousands, or even millions of years. There wouldn't be an observational record of them, but there would likely be a geological record. My initial thought is that I don't recall any clear periodicity in mass extinctions in the fossil record, but I'm not even remotely an expert in this field.

    Posted 7 years ago #
  21. Kevin C.

    Not to discount the idea of unknown debris cloud, but they should behave like known meter swarms, in that they all follow roughly the same trajectory. So during the Persieds most seem to radiate from the constellation Persius; the Leonads from Leo, and so on. These seem to be coming from different directions, indicating significantly different orbits.

    However, what if there are periodic events where rocks in different orbits happen to coincide in roughly the same place at the same time? Think of it like a fancy clock where all the hands happen to point in the same direction at the same time, though each hand rotates at a different rate. If you know the rate of rotation of each hand, you can predict the occurrence, just as it's possible to predict eclipses.

    However, unlike clock hands, we don't know how many rocks are out there, what their orbits are, or whether they pass close enough to other objects to affect their orbits. Still, odds are that the orbits of several may cross the earth's just as we're spinning by, then we get several events in a short span of time. They're each in their own different orbit, just the clock hands happened to line up.

    Posted 7 years ago #
  22. AKAkarlb

    Geoff, check out this:

    The current verdict seems to be "not proven," though there is apparently some evidence for periodic extinction events.

    I remember when Raup and Sepkoski proposed the possibility of an unknown solar companion causing periodic debris showers at very long intervals. The consensus at the time was that something distant and faint enough to avoid detection was unlikely to have a stable-enough orbit around the Sun to hang around for hundreds of millions of years.

    IMO, the current apparent blitz of asteroids is purely an artifact of the intensified search for such, and the heightened awareness of them since the Russian meteor.
    It's estimated that 95% of big (1/2 kilometer and up) Near Earth Asteroids have been located and orbits calculated - none pose any apparent risk, happily, because these are the ones that would do real damage no matter where they hit. There are thousands of them. The small house-sized objects are far more numerous but much harder to detect, which is why they frequently are found only days before closest approach.

    Posted 7 years ago #
  23. geoffhart1962

    Kevin: the "clock hands" metaphor is precisely what I was trying to say, only you said it so much more clearly. Nicely done!

    AKAkarlb: If you take the clock hands metaphor and use a time period measured in geological rather than human terms, you'll have a better idea of what I was getting at. That's the hypothesis I'd like to see tested, but you'd need paleogeological rather than historical evidence because the data would extend beyond the period of written or oral records.

    For example, is there a database of all known meteor craters on Earth or the moon in which the craters been dated based on the estimated time of impact? If so, are there any cyclical patterns in those ages? I don't know of any such thing, but again, I'm not an expert.

    Posted 7 years ago #
  24. AKAkarlb

    Geoff: yes there is a database:

    It's maintained at the Planetary and Science Center at the University of New Brunswick, a logical place since the Canadian Shield AFAIK is the largest area of really old (2 billion years or so) exposed rock in the world. Also it's been scraped by glaciers several times so the bedrock is closer to the surface than it otherwise would be and structures that otherwise might be buried, like the Manson crater in Iowa ( are much more apparent than you'd think.

    One of them is the Manicouagan crater mentioned in the database link, which was a whopper:

    I remember when there was speculation that this one might have a connection to late Triassic extinctions, though the wiki article says this is no longer believed to be so, why I don't know, maybe the date is wrong. There is strong evidence that it was one of a series of multiple impacts that happened at the same time; see the wiki article.

    Another example: Clearwater Lakes, apparently formed by the impact of a double asteroid (they are not uncommon):

    Asteroids are not evenly distributed. They do form families:

    and there are areas in the main belt where there are few if any asteroids:

    It has been hypothesized that Jupiter, in addition to forming the Kirkwood gaps, has served as a protective mechanism for the inner Solar System in that its gravity flings many comets out of the system that otherwise might impact the Earth at one time or another. We may owe the existence of life on earth to Jupiter. On the other hand, there is also evidence that it increases the number of inner system asteroids:

    Anyway, to return to your original question, whether or not there are periodic showers of impacts would be very hard to determine for the earth since most would hit in the ocean and craters eventually be destroyed by seafloor spreading and subduction under tectonic plate boundaries, unless they hit on continental shelves. (The mouth of Chesapeake Bay is an impact structure, for example).

    There is some evidence for periodicity in extinction (see the Nemesis article I posted above) and the only mechanism that anyone has proposed for that is extraterrestrial, i.e. impact events. But it is still very early days for any of this; the idea that impacts could have any affect whatsoever on earth is only about 50 years old and really didn't gain much traction until the Alvarezes announced the iridium layer at the K/T boundary in 1980.

    Anyway, thanks for posing the question, you prompted me to refresh my knowledge of all this and a lot has been discovered in the last few years.

    Posted 7 years ago #
  25. AKAkarlb

  26. Marian

    Phil Plait gives an excellent summary. I love his last lines
    "Holding that asteroid sample in my hand makes the hair on the back of my neck stand up. What history does it have? What events and objects did it encounter over its 4+ billion year lifetime spent orbiting the Sun, before one sunny morning a blue-green planet swelled into view, blocking its path"

    Posted 6 years ago #
  27. Marian

    Another insterstellar comet has appeared. Is this getting more common or are we getting better at detecting comets?

    Posted 8 months ago #

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