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Space Earth

Comet Nearly Hit Earth? Not So Fast 84

Posted by timothy from the leap-from-conclusions dept.
Phil Plait ("The Bad Astronomer") writes with a skeptical take on the recent report that a comet may have narrowly missed earth. According to the linked post from Plait, "When a comet breaks up, it spreads out. Even when intact, the material surrounding a comet can be tens or even hundreds of thousands of kilometers across! Claiming that a comet broke apart, yet managed to constrain its pieces to volume of space less than a few thousand kilometers across strains credulity. Mind you, Bonilla claimed to have seen these objects over the course of two days. That means they would’ve been stretched out along a path that was a million km long at least, yet so narrow that only one observatory on Earth saw them transit the Sun. That is highly unlikely. Worse, the very fact that no one else saw anything makes this claim even less tenable."
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Comet Nearly Hit Earth? Not So Fast More

Comet Nearly Hit Earth? Not So Fast

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  • I want a Good Astronomer (Score:5, Funny)

    by ArcherB ( 796902 ) on Tuesday October 18, 2011 @08:51AM (#37748750) Journal

    Why would I trust the opinion of someone who calls himself "The Bad Astronomer". I want the opinion of a GOOD Astronomer!

    It's like wine. How about some fresh wine. And bring me those finger sandwiches you talked me out of!

    • It's like wine. How about some fresh wine. And bring me those finger sandwiches you talked me out of!

      Hey, we said astronomy, not gastronomy!

    • Re: (Score:2)

      by Goaway ( 82658 )

      The good ones have better things to do than look at garbage papers on arXiv, I guess.

    • Man, you're a jerk!

    • Re:I want a Good Astronomer (Score:4, Informative)

      by delt0r ( 999393 ) on Tuesday October 18, 2011 @10:21AM (#37749556)
      I assumed people would get the Joke. Apparently not. The blog is well respected in Astronomy circles and he publishes peer review papers in the field. He is in fact a good Astronomer.

      I assume parent knows this... hence the quip about fresh wine.
    • I actually like "fresh" wine. Every year in Germany (I lived there for three years), we'd go to the wine fests and drink "new" wine. It still had the CO2 fizziness - yum. Oh wait, did I say CO2, I'm sure to get modded flamebait for that one. I like mature wine as well, but I fondly remember the new as well.

      • I actually like "fresh" wine. Every year in Germany (I lived there for three years), we'd go to the wine fests and drink "new" wine.

        For those that wonder what it is: Federweißer [wikipedia.org].

      • I actually like "fresh" wine.

        For some wines fresh is the way to go - they're called vins de primeur. The best known is the Beaujolais nouveau [wikipedia.org], which doesn't normally keep over one year.

    • His blog is Bad Astronomy. He doesn't call himself the Bad Astronomer. Hate to be a humorless correctofreak but I'm sick of sloppy postings.
    • I know that this was a joke, but I think the point was to get "badass" in his title

  • Unless it very recently broke up.

    Pretty visible scatter, but not scattered enough to impact.

  • That's what I said! (sort of) (Score:3)

    by wisebabo ( 638845 ) on Tuesday October 18, 2011 @09:07AM (#37748868) Journal

    Ok I wondered why we didn't get HIT by some of the pieces of the comet instead of more people seeing it but then again I'm not an astronomer (good or bad).

    Here's my previous post:

    While it is not impossible that an extinction level event almost happened, I'd like to see a bit more evidence before panicking.

    If this comet was so close, so much so that no other observatory on earth was able to see it due to "parallax", how come not one of the 450 or so pieces impacted the earth? (There are no reports of Tunguska sized impacts).

    Also, wouldn't it be relatively easy to figure out where this thing was headed and find out where it is now? Unless it was a (very) long period comet or ended up in the sun, we should be able to track it down. In fact, if it exists, shouldn't it be easy to find as it will likely have an orbit that repeatedly intersects earth's orbit? (Ulp!)

    Anyway, some slashdotters who read this post commented that it could be very hard to tell where the pieces could have ended up due to the chaotic influence of the earth's gravity. True but we're talking about something pretty big (a billion tons) that came within a hairs breadth of hitting the earth, you'd think there would be enough information in the observation to plot some of these large objects spewing gas and plumes. Likewise, the very fact that it came within (I think the article said a few hundred kilometers) means that, regardless of orbital inclination, it's orbit DID intersect that of the earth's orbit and presumably sone of the pieces would continue to do so in a very visible fashion (unless it is a long period comet or plunged into the sun!).

    But then again I'm not an astronomer so who knows?

    • While what you say makes solid sense, I would like to interject that this was a past event during a way different time, when communication were slow.
      What might now be occurring is that other observatories are going back to those dates to see if anything was documented. I think people in those days kept log books. OR it could be just that someone played a real good joke on the guy OR maybe validation will come around over the next 20 years or so.

      • While what you say makes solid sense, I would like to interject that this was a past event during a way different time, when communication were slow.
        What might now be occurring is that other observatories are going back to those dates to see if anything was documented. I think people in those days kept log books.

        That's a fair point, but I'd like to point out that the logs of many of these observatories have already been studied in detail, since despite using more primitive instruments their observations provide important data for astronomy today.

        For example, there is known to be extensive documentation of the Leonids meteor shower from those days, in particular a massive instance of the shower from 1833. It was recorded not just by astronomers but by many other sources.

        If fifty years later a comet had passed that

        • Now I ask something interesting, is it possible that from the position of the observatory gave it an advantage over other observatories ? reason is, that if there was an advantage, it would seem that the discovery might be found in observatory at a similar longitude ( Florida, Egypt, India southern china )

          • I used to live in Arizona, and I know that the lack of moisture, clouds, etc make the desert prime for seeing the night sky in an impressive display I've never seen anywhere else. Do we have any idea of the weather around the world at that time? Can we account for every possible scenario that might cause a particular observatory not to have anyone on staff to see this comet (weather, holiday, sick)? Was the comet visible to the naked eye? What if the other observatories were aligned to look at somethin

          • The observations were repeated on successive days. Given the length of night at that site and the time of year, that means that they were at least 13 hours from start of first observation to end of last observation. Because the observatory passed through the night between observations, and the (alleged) comet was between the observatory and the sun ... then every observatory on the antipodal side of the planet to the observatory was better placed than this observatory.

            The reported observations were from Me

    • Re:That's what I said! (sort of) (Score:4, Insightful)

      by Pharmboy ( 216950 ) on Tuesday October 18, 2011 @09:42AM (#37749180) Journal

      If this comet was so close, so much so that no other observatory on earth was able to see it due to "parallax", how come not one of the 450 or so pieces impacted the earth? (There are no reports of Tunguska sized impacts).

      While I agree with your skepticism, considering this was pre-radio era, and that we might have had some impacts on water and just didn't know it. The earth is over 2/3rds water, after all, so odds are always that a meteorite will hit water, not land. There is also the possibility that we were hit with many, many smaller meteorites (smaller than a Hyundai) over mainly water. Or the fact that comets are often made of water ice, so most of what hit the atmosphere either evaporated on the way down or shortly thereafter. If a chunk of water ice had hit the planet anywhere over 100 years ago, odds were certainly in the favor of it hitting either water or uninhabited land.

      Yes, we need more evidence, but it does seem worth the time and effort for someone more knowledgeable than you and I to research a bit more. As for the question "Will Earth experience near misses?", the answer is an obvious "yes", since we also get major hits every 130 million years or so, so the idea that this did happen is at least plausible.

      • Forget impacts, the most damning piece of evidence to me is that nobody saw a giant comet at night on our doorstep. Aren't comets known for their visibility *millions* of miles away? But this one is somehow a stealth comet that nobody sees except when silhouetted against the sun?

    • >> While it is not impossible that an extinction level event almost happened, I'd like to see a bit more evidence before panicking.

      Why would you want to panic ?

      1) If there was a risk in the past, we don't care.

      2) If there is a risk in the future, we don't care also, coz past T0, we are back in situation 1 (or we are all just dead)

      • Sorry, I should have made this point clear in my post.

        If the comet came within a whisker of hitting us before, there's a not-insignificant chance it'll do so in the future. It's got an earth crossing orbit with an inclination that intersects our own orbit. If it's been broken up (as claimed in the original article) there's an even better chance that one of those (big) fragments is gonna whack us on the next go around.

        Consider Apophis (the asteroid). In 2029 it's gonna come uncomfortably close to the eart

    • Re:That's what I said! (sort of) (Score:4, Funny)

      by JSBiff ( 87824 ) on Tuesday October 18, 2011 @10:52AM (#37749960) Journal

      "While it is not impossible that an extinction level event almost happened, I'd like to see a bit more evidence before panicking."

      Why would anybody panic about something which didn't happen in the past? Little bit late for panicking now, wouldn't you say?

      • (This is a repeat of a post above). Sorry, I should have made this point clear in my post.

        If the comet came within a whisker of hitting us before, there's a not-insignificant chance it'll do so in the future. It's got an earth crossing orbit with an inclination that intersects our own orbit. If it's been broken up (as claimed in the original article) there's an even better chance that one of those (big) fragments is gonna whack us on the next go around.

        Consider Apophis (the asteroid). In 2029 it's gonna

        • If the comet came within a whisker of hitting us before, there's a not-insignificant chance it'll do so in the future. It's got an earth crossing orbit with an inclination that intersects our own orbit. If it's been broken up (as claimed in the original article) there's an even better chance that one of those (big) fragments is gonna whack us on the next go around.

          Consider Apophis (the asteroid). In 2029 it's gonna come uncomfortably close to the earth. In 2036 (I think) there's a chance that it'll hit us

    • Unlikely != Impossible (Score:4, Interesting)

      by mveloso ( 325617 ) on Tuesday October 18, 2011 @11:16AM (#37750204)

      Life is apparently extremely unlikely, yet here we are.

      How many astronomers do observations during the day today? Roll back 100+ years and the number likely drops tremendously. The guy is staring at the sun! Who does that on a daily basis?

    • Also, wouldn't it be relatively easy to figure out where this thing was headed and find out where it is now?

      "relatively easy" for certain values of "easy" starting at "extremely difficult" and extending towards the impossible.

      Firstly, the records are pretty sparse ; effectively we've only got two putative measurement points, and each of those has an accuracy of less than a half-degree (the angular size of the sun). IF (and it is a real "if") there exists a possible Keplerian solution for such an object tha

  • meteorites impacting earth daily (Score:5, Informative)

    by IAR80 ( 598046 ) on Tuesday October 18, 2011 @09:09AM (#37748882) Homepage
    The number of meteorites impacting the earth daily is in the hundreds if not thousands. Most of them are so small that they bun up in the upper atmosphere. On average 2 every day are big enough to make it through the atmosphere and reach earth. If the comet was fragmented into tiny pieces it would not matter.
    • To be slightly pedantic, all meteorites impact the earth. If it burns up in the atmosphere without impacting earth it's just called a meteor.

    • Re: (Score:2)

      by Tim C ( 15259 )
      Impacting the Earth and burning up in its atmosphere are not the same thing. Also even if the comet was fragmented small enough to ensure that none of it hit the ground, we'd still be looking at it dumping a huge amount of energy into the atmosphere, the effects of which would likely be rather unpleasant.

  • Phil Plait is not a bad astronomer (Score:3)

    by Walter White ( 1573805 ) on Tuesday October 18, 2011 @09:33AM (#37749086)

    He writes a column debunking "Bad Astronomy."

    • Yes, and @BadAstronomer is his username on Twitter. It's a nickname.

  • If this really happened, there should be a train of comet debris that the earth would pass through each year creating The Mother-of-All Meteor Showers on August 10-13 but this has not happned. Sounds like migrating birds; the migration has definitely started by then and in the old days when there were a lot more neo-tropical migrants, birder would focus their scope on the moon to watched the migrants pass by.

    • Re: (Score:2)

      by mikael ( 484 )

      Much like the New Madrid earthquake, there was a report around those years on a couple of nights when the sky glowed red, and night-time became as hot and humid as day. There were some theories it was the Earth traveling through the tail-end of a comet ,as it coincided with meteorite showers.

  • Not so fast? (Score:1)

    by Anonymous Coward

    Comet Nearly Hit Earth? Not So Fast

    OK, as you wish:

    Coooommmmehhhhhht Neeeeeeaaaaarrrrrllllllyyyyy Hiiiiiiiit Eeeeeaaaaarrrrrrrth?...

  • I agree with BA on this one. This story doesn't add up. If you presume they were looking at pieces transiting the sun over 2-3 days, then you have to assume that the narrow window of parallax in which to observe the transit existed for 2-3 days in the same location on Earth. THAT IS HIGHLY IMPROBABLE. The comet would have had to have an orbit directly on-plane to earths orbit to begin with for this to happen, and if that were so and the comet fragment were so close to us, we would have had to have directly
    • Then, what did this guy see? Is he a liar? I presume he saw something. It must be the Reptilian's or the Gray's space fleet.

      • Re: (Score:1)

        by Anonymous Coward

        Then, what did this guy see? Is he a liar? I presume he saw something. It must be the Reptilian's or the Gray's space fleet.

        Or a teapot [wikipedia.org].

    • I agree. Also, this is a "comet." Wouldn't a comet develop a "coma" (aka, tail) as it approaches the sun? They are visible for several days just before sunrise or after sunset. With all those pieces out there and being so close to earth, some of them had to be large enough to develop a coma and consequently put on quite a display.

  • ... it was in 1883. How many observatories did Earth even HAVE back then? This was before radar, before computers, before telephones. Normal photography was in its infancy and astrophotography didn't exist yet. Telescopes were still aimed by hand. Whatever it was, I can easily believe that only one guy on Earth just happened to be observing the Sun during daytime and saw a transit of objects that nobody else reported.

  • The 2011 paper can be read here: http://arxiv.org/ftp/arxiv/papers/1110/1110.2798.pdf [arxiv.org]
    Bonilla's 1885 paper can be read here: http://gallica.bnf.fr/ark:/12148/bpt6k2096403/f351 [gallica.bnf.fr]

    • The 2011 paper can be read here: http://arxiv.org/ftp/arxiv/papers/1110/1110.2798.pdf [arxiv.org]
      Bonilla's 1885 paper can be read here: http://gallica.bnf.fr/ark:/12148/bpt6k2096403/f351 [gallica.bnf.fr]

      The... interesting font choice and yahoo email address as primary contact do not instill a sense of confidence in the 2011 paper. That, and it doesn't appear to have been published anywhere other than arxiv.org. Maybe at least wait for it to make it through peer review before having big discussions about it? This is one of the problems with arxiv.org - it is an archive of preprints, which may or may not have gone anywhere. From arxiv.org:

      Disclaimer: Papers will be entered in the listings in order of receipt

  • August 1883 perhaps? Exactly how many observatories were in the world in 1883? Exactly where were they located and how many were actively watching the sky? It's not like the technology of the day allowed for claims to be corroborated or recorded in real time.

    I'm not saying the original article doesn't have holes, but if you are going to be skeptical about the claim, at least be honest and include both sides of the skepticism.

    • I presume the bad astronomer has some idea of how many observatories were around back then. However, I also find it unlikely that more than 1 or 2 people would have seen this comet.

    • Re: (Score:2)

      by k6mfw ( 1182893 )

      I was thinking the same thing, probably other astronomers (not many then as now) probably saw something but did not document. Like the big supernova around 1000 AD, very little documentation from what I understand only a reference in Chinese writings. During this time everyone in Europe were too focused on religious stuff, wars, and torturing people.

      Like we say nowadays, "pics or it didn't happen" and for scientists, "publish or perish."

  • First, the Bad Astronomy blog is a great resource, and the comments are often witty, informative, and/or insightful.

    BUT, what's with all the god-damned emoticons in the comments there?

    I have to read the blog with image loading turned off, because each one is like a laser pointer shining in my eyes. Sometimes an otherwise intelligent & thoughtful commenter will put 2 or more in a single comment. Today's posting had a comment with 2 in a row.

    Damnit, that's annoying. If they were only textual emoticons,

  • Isn't there a rule that until someone else sees it, it just doesn't exist. So the mere fact that no one else saw it, MEANS, per rule, it don't exist.

    --
    Simply disagreeing with a comment is not a valid reason to mark it down.
    --CmdrTaco

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