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Comet Nearly Hit Earth? Not So Fast

timothy posted more than 2 years ago | from the leap-from-conclusions dept.

Space 84

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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84 comments

Shoemaker–Levy 9 (0)

Anonymous Coward | more than 2 years ago | (#37748724)

Shoemaker–Levy 9 didn't look scattered all over the place, pretty much looked like a straight line.

Wait! Use this! (-1, Troll)

ZeroHoles (2487746) | more than 2 years ago | (#37748830)

Don't read this... it is a curse...

In 2003, a little boy named Cody was walking down the sidewalk, going to a nearby store. Suddenly, he was transported into a large dark alley. After recovering from the initial shock of him being transported from his previous location, he noticed that something was horribly wrong; his clothes weren't transported with him! After stumbling around in the dark alley for a few seconds, Cody heard evil laughter and whispers coming from all around him. He began running around and looking for an exit whilst thinking about the two entities that he instinctually knew were chasing him. Then, to his horror, he tripped and fell face-first onto the ground and could no longer move a single cheek!

He then felt two entities jump onto both of his bootyasscheeks. Then, his vision was transported elsewhere and he found himself staring at his own body as if he was looking at himself through a security camera. The two entities were toys! He saw the toys get ready to jump up his butt after saying, "Reaaaaady?" However, just before they could jump into his bootyass, a strange figure appeared in the darkness and said, "Wait! Use this!"

The toys replied, "Whaaaaaat dooooooes iiiiiiit dooooooo?" The strange man said, "Iiiiiiiiiit puuuuuuuts iiiiiit uuuuuup hiiiiiis buuuuuuuuuuuuuuuutt!" Then, a strange machine appeared out of nowhere, moved its mechanical arm, and dropped a counterfeit US quarter into Cody's bootyass! It inflicted tremendous amounts of tickle upon his bootyass, and it sounded like a quarter going down a slot machine!

Now that you have read this (even a single word of it), the strange man will use his machine to insert counterfeit US quarters into your bootyass (thereby inflicting ridiculous amounts of tickle upon it)! To prevent this from happening, copy and paste this entire comment and then repost it as a comment three times.

Re:Shoemaker–Levy 9 (1)

Jappus (1177563) | more than 2 years ago | (#37749264)

Shoemaker–Levy 9 didn't look scattered all over the place, pretty much looked like a straight line.

And the 21 fragments whose impacts were visible from earth needed 6 days to hit the planet. 6 days at a speed of ~60 km/s equals ~ 31 million kilometers distance between the first and last impactor.

So the submitter is indeed right: "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."

Re:Shoemaker–Levy 9 (3, Informative)

Chris Burke (6130) | more than 2 years ago | (#37750080)

Shoemakerâ"Levy 9 didn't look scattered all over the place, pretty much looked like a straight line.

The pieces large enough to be visible from Earth, and where "pretty much" is relative to the size of Jupiter.

If the major remnants of a broken comet had passed that close to earth, then the millions of tiny remnants would have created a meteor shower on earth that would put the Leonids to shame.

I want a Good Astronomer (4, Funny)

ArcherB (796902) | more than 2 years ago | (#37748750)

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!

Re:I want a Good Astronomer (2)

fph il quozientatore (971015) | more than 2 years ago | (#37748808)

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:I want a Good Astronomer (0)

Anonymous Coward | more than 2 years ago | (#37748904)

Untranslatable, but relevant if you understand Dutch: "Astronomie gaat over kometen, gastronomie gaat over gaan eten."

Re:I want a Good Astronomer (2)

Whalou (721698) | more than 2 years ago | (#37749070)

Somewhat funny after Google translate:

Astronomy is about comets, gastronomy is about to eat.

Re:I want a Good Astronomer (2, Informative)

Anonymous Coward | more than 2 years ago | (#37749648)

The humor part is that in Dutch: "kometen" (comets) sounds the same as "kom eten" (come eat).

A loose translation of the wrong interpretation would be: Astronomy is about coming in to eat, gastronomy is about going out to eat.

Re:I want a Good Astronomer (0)

Anonymous Coward | more than 2 years ago | (#37749102)

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

Considering the original paper was written in Comic Sans, I'm more inclined to trust this "bad" astronomer.

http://arxiv.org/pdf/1110.2798v1 (the paper, PDF)

Re:I want a Good Astronomer (1)

Goaway (82658) | more than 2 years ago | (#37749420)

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

Re:I want a Good Astronomer (3, Informative)

delt0r (999393) | more than 2 years ago | (#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.

Re:I want a Good Astronomer (1)

Taty'sEyes (2373326) | more than 2 years ago | (#37749586)

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.

Re:I want a Good Astronomer (1)

V for Vendetta (1204898) | more than 2 years ago | (#37751262)

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].

Re:I want a Good Astronomer (1)

ChatHuant (801522) | more than 2 years ago | (#37754286)

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.

Re:I want a Good Astronomer (1)

almitchell (1237520) | more than 2 years ago | (#37749782)

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.

Re:I want a Good Astronomer (0)

Anonymous Coward | more than 2 years ago | (#37750614)

I agree with your sentiment on the sloppy postings, but Mr. Plait /does/ use the twitter handle BadAstronomer.

Re:I want a Good Astronomer (0)

Anonymous Coward | more than 2 years ago | (#37750708)

You're not a humorless correctofreak, you're a clueless one. The Bad Astronomer himself has posted stories on /. under the name (wait for it) The Bad Astronomer.

Re:I want a Good Astronomer (0)

Anonymous Coward | more than 2 years ago | (#37751026)

Actually he does, and his twitter handle is @BadAstronomer

Krakatoa (0)

Anonymous Coward | more than 2 years ago | (#37748796)

I also notice that this claimed observation was 2 weeks before the Krakatoa eruption (and was also during the Perseid meteor shower). Perhaps the observer was "distracted" at some point while developing his plates?

Re:Krakatoa (1)

Squidlips (1206004) | more than 2 years ago | (#37753472)

The Krakatoa eruption was a long drawn out affair with a lot of violent volcanic activity before it blew its top off. Still Occam's Razor would suggest that migrating warblers, vireos, and thrush were what was being seen. He was right in line of the migration route at the right time of year and thousands of birders have seen these shapes during migration.

I didn't see it, therefore it didn't happen (0)

Anonymous Coward | more than 2 years ago | (#37748818)

In science it's necessary to be skeptical, but drawing a conclusion without a rigorous examination of the data is just lazy speculation and indicative of bad science.

That's what I said! (sort of) (2)

wisebabo (638845) | more than 2 years ago | (#37748868)

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?

Re:That's what I said! (sort of) (2)

onepoint (301486) | more than 2 years ago | (#37748998)

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.

Re:That's what I said! (sort of) (1)

Chris Burke (6130) | more than 2 years ago | (#37750236)

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 close to earth then the resulting shower of small comet fragments would have dwarfed the 1833 Leonids and would have been recorded by a great many observatories, plus newspapers and other sources. There wouldn't be a paper saying "Hey, we think what this one guy in Mexico saw was a comet that passed near earth and nobody else saw it", there'd be a paper saying "Hey, we think we found an observation of the comet that was the source of the well-document but heretofore mysterious 1883 Meteor Shower."

In the latter scenario this would start to sound pretty plausible. That's just not the scenario we're dealing with.

Re:That's what I said! (sort of) (1)

onepoint (301486) | more than 2 years ago | (#37757500)

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 )

Re:That's what I said! (sort of) (1)

Nox3173 (1495587) | more than 2 years ago | (#37758562)

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 something else - is it possible to miss one event while looking at another? This would be especially relevant if the comet was not visible to the naked eye i would think.

Re:That's what I said! (sort of) (1)

RockDoctor (15477) | more than 2 years ago | (#37761280)

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 Mexico City (approximately). The antipode is around the India - Indonesia - East Africa longitude (the 13 hour implied duration also implies an arc of at least 195 degrees which passed through the sub-solar point, and therefore through the sub-cometary point). Not the most highly developed of areas, particularly at that time, but with significant historical activity in astronomy. So I'd be pretty surprised if there were no active observers at the time.

Re:That's what I said! (sort of) (3, Insightful)

Pharmboy (216950) | more than 2 years ago | (#37749180)

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.

Re:That's what I said! (sort of) (0)

Anonymous Coward | more than 2 years ago | (#37752010)

"near miss" that phrase always bothers me, if you nearly missed the target, you hit it! It should be a "near hit." I don't know why, it just bugs me... almost as much as people that misspell "a lot" as one word.

Re:That's what I said! (sort of) (0)

Anonymous Coward | more than 2 years ago | (#37753882)

Seriously? "near miss" makes perfect sense. It was a miss but it was "near"ly a hit. A "near hit" would be ... redundant...

Redundant to tell us exactly what it nearly was? (0)

Anonymous Coward | more than 2 years ago | (#37753978)

But why do we know that it was nearly a hit, as opposed to (say) nearly a pot of petunias?

Re:Redundant to tell us exactly what it nearly was (1)

Pharmboy (216950) | more than 2 years ago | (#37757180)

Is the glass half empty or half full? Either expression would describe the event I suppose, most of us just choose to use "near, but missed" or "near miss", which is less confusing.

Re:Redundant to tell us exactly what it nearly was (0)

Anonymous Coward | more than 2 years ago | (#37772994)

"Near, but missed" is two independent things; "but" means, logically, exactly the same thing as "and". It was near. It missed. It was not a "near miss", because then "near" applies to the word "miss", not the word "it".

"Half empty" and "half full" mean exactly the same thing, by the way. Six one way and half a dozen the other. A better example would be "nearly empty" and "nearly full", because it can't be both at the same time.

Re:That's what I said! (sort of) (1)

im_thatoneguy (819432) | more than 2 years ago | (#37752064)

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?

Panic ???? (1)

stooo (2202012) | more than 2 years ago | (#37749958)

>> 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)

Re:Panic ???? (1)

wisebabo (638845) | more than 2 years ago | (#37750298)

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 earth. In 2036 (I think) there's a chance that it'll hit us. (I think this scenario will repeat into the future with decreasing probabilities). Now imagine that, instead of a single body, it was a stream of fragments "a million kilometers long". I think the chance of impact would go way up.

Remember that comet that hit Jupiter? (I think it was Shoemaker Levy) It made a close pass by Jupiter first which tore it apart (just like this comet is supposed to have done) then came back and broadsided the planet on a subsequent orbit. (In fact I think that's how they were able to get advance warning of the event and train a lot of telescopes on it, they saw it was going to make another close approach).

So, it's right to (perhaps moderately) panic if this was a close call until we can figure out where it went.

Re:That's what I said! (sort of) (3, Funny)

JSBiff (87824) | more than 2 years ago | (#37749960)

"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?

Re:That's what I said! (sort of) (1)

wisebabo (638845) | more than 2 years ago | (#37750322)

(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 come uncomfortably close to the earth. In 2036 (I think) there's a chance that it'll hit us. (I think this scenario will repeat into the future with decreasing probabilities). Now imagine that, instead of a single body, it was a stream of fragments "a million kilometers long". I think the chance of impact would go way up.

Remember that comet that hit Jupiter? (I think it was Shoemaker Levy) It made a close pass by Jupiter first which tore it apart (just like this comet is supposed to have done) then came back and broadsided the planet on a subsequent orbit. (In fact I think that's how they were able to get advance warning of the event and train a lot of telescopes on it, they saw it was going to make another close approach).

So, it's right to (perhaps moderately) panic if this was a close call until we can figure out where it went.

Re:That's what I said! (sort of) (1)

CrimsonAvenger (580665) | more than 2 years ago | (#37752684)

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. (I think this scenario will repeat into the future with decreasing probabilities). Now imagine that, instead of a single body, it was a stream of fragments "a million kilometers long". I think the chance of impact would go way up.

The assumption that the length of its orbit is an even multiple of 1 year is what allows you to believe this. If, instead, it's orbit were, say, 500 years and 2.7 days long, it'll be about 270,000 years before it came close again. And it wouldn't be close enough then for a collision if it were only a million km long. For it to be a threat in my hypothetical, you'd be waiting about 125 million years.

Note that in the above hypothetical case, it won't even come into viewing distance again for another 370+ years, much less be a threat to us.

Note that there are more orbits where it won't come back this way for a VERY long time than there are orbits where it'd be back on its next pass....

The fact that Shoemaker-Levy hit Jupiter was more a result of it being in orbit around Jupiter (as opposed to being in orbit about the Sun and happening to pass Jupiter close on two subsequent orbits) than anything else. Note that there's no indication that this comet (even if it existed) is in orbit around Earth.

Unlikely != Impossible (3, Interesting)

mveloso (325617) | more than 2 years ago | (#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?

Re:That's what I said! (sort of) (1)

RockDoctor (15477) | more than 2 years ago | (#37761652)

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 that fits with the records, then that orbit will be quite imprecise precisely because we don't know where the centre of mass of the object was, merely that some of the particles were within the half-degree area of the Sun's disc. Pick your model for where the centre of mass is - I'd probably start by modelling the first estimates for the centre of mass to lay on a circle of a degree in diameter, concentric with the solar disc - work out the range of Keplerian solutions for each pair of possible observations (say, 4 points at each observation, for 16 possible orbits)

Oh, now you've got 16 possible orbits. But that's still "relatively easy".

How close do these orbits approach the Earth? Because that is going to severely affect the amount by which the orbit is perturbed, both going forward and backwards in time. You're going to face this problem every time the orbit approaches that of the Earth. And the Moon. And the rest - the orbit-tracking code that the MPC uses includes the effects of all the planets, satellites and some of the larger asteroids. (MPC - Minor Planets Centre, the clearing house for observations of minor planets, including potential hitters. Oh, they've moved websites : http://minorplanetcenter.net/iau/mpc.html [minorplanetcenter.net] )

It all gets literally chaotic, very rapidly.

The absence of other observations of cometary fragments around this time is strong evidence that there wasn't a close approach by a comet then. It may not have been as widely discussed a topic then as today (walk down the street today and find how many people know what a "Potentially Hazardous Asteroid" is ; you won't find many people who know, or care), but some people certainly knew what the potential of an impact was, in general terms. The 1910 apparition of Halley's comet was accompanied by significant media hysteria about the closeness of the comet to the Earth. I don't think it credible that 22 years previously, not one person put two and two together to report on an unusual coincidence of comets. Having Hyakutake and Hale-Bopp so close together excited noticeable attention a couple of years ago ; imagine actually having two comets extremely close together in time and in the sky, and moving extremely fast (because they're nearby) - how much attention would that have gathered. Remember too, that this was a time when light pollution was much less extensive.

meteorites impacting earth daily (4, Informative)

IAR80 (598046) | more than 2 years ago | (#37748882)

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.

Re:meteorites impacting earth daily (0)

Anonymous Coward | more than 2 years ago | (#37749012)

Moreover, I imagine that if a fairly large sized chunk of this thing had landed in the ocean or in a very remote area, nobody would have known about that event. Given that 2/3 of the Earth's surface is water, plus vast uninhabited areas, it seems at least plausible that some bits did hit the Earth.

Re:meteorites impacting earth daily (0)

Anonymous Coward | more than 2 years ago | (#37749020)

Meteorites are called meteorites because they're small. We're not talking about a cometite here.

Re:meteorites impacting earth daily (0)

Anonymous Coward | more than 2 years ago | (#37749186)

Meteorites are called meteorites because they're small.

Wow. Not sure how you got that impression. Meteorites are called Meteorites because they HIT THE EARTH. They are Meteors when they burn up in the atmosphere and Meteorites if they land. As Wikipedia says, "Meteorites can be big or small".

Re:meteorites impacting earth daily (0)

Anonymous Coward | more than 2 years ago | (#37749074)

Nothing about that makes any sense. There is a difference between meteor and meteorite. If hundreds impact the earth, that does not mean all but 2 burned up in the atmosphere. That would change the average daily that make it through the atmosphere to "hundreds if not thousands".

Re:meteorites impacting earth daily (1)

monkeyhybrid (1677192) | more than 2 years ago | (#37749092)

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:meteorites impacting earth daily (1)

Tim C (15259) | more than 2 years ago | (#37750730)

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.

Re:meteorites impacting earth daily (0)

Anonymous Coward | more than 2 years ago | (#37751598)

According to wikipedia, there are hundreds of impacts of meteorites per year. On average, 2 per day.

http://en.wikipedia.org/wiki/Meteorite#Fall_phenomena [wikipedia.org]

There are also thousands and thousands of a lot smaller particles that will not burn up on re-entry - they are too small.

Anyway, a comet hitting the earth would be quite unpleasant.

Phil Plait is not a bad astronomer (2)

Walter White (1573805) | more than 2 years ago | (#37749086)

He writes a column debunking "Bad Astronomy."

Re:Phil Plait is not a bad astronomer (-1)

Anonymous Coward | more than 2 years ago | (#37749288)

"Debunking" isn't part of his column name. Sorry but I'll ignore the guy until he fixes that.

Re:Phil Plait is not a bad astronomer (1)

delt0r (999393) | more than 2 years ago | (#37749520)

In Astronomy circles its a pretty famous blog and well respected. The guy publishes peer reviewed papers in the field.

Re:Phil Plait is not a bad astronomer (1)

Things_falling_apart (856111) | more than 2 years ago | (#37749614)

His original site was all about debunking myths and misconceptions related to astronomy. Here is the link to his original site: http://www.badastronomy.com/index.html [badastronomy.com] He changed to a blog format when he joined the discover magazine network. His name refered to him pointing out bad astronomy in the movies and TV. Not really all that hard to understand why he has his name. He got pretty well known and discover magazine put him on the payroll and since he was well known, he kept his moniker.

Re:Phil Plait is not a bad astronomer (1)

Chris Burke (6130) | more than 2 years ago | (#37750122)

"Debunking" isn't part of his column name. Sorry but I'll ignore the guy until he fixes that.

Thus demonstrating your superior intellect and keen discernment.

Where's the meteor shower? (1)

Squidlips (1206004) | more than 2 years ago | (#37749160)

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:Where's the meteor shower? (0)

Anonymous Coward | more than 2 years ago | (#37749730)

Not necessarily. There's no reason to believe that the comet - if it existed - had a period of one year. nor to believe that the debris wasn't then pulled into another orbit, or any of a great many other reasons why we may not see that debris field again for a good long time if ever.

Which isn't to say I believe the comet existed, but rather that our not passing through/by its debris field annually isn't probative.

Re:Where's the meteor shower? (1)

Squidlips (1206004) | more than 2 years ago | (#37753388)

No, no, no you guys missed the point. A comet does not have to have a 1 year orbit for this to happen; the train lasts for decades. The debris train from this putative comet would be massive and create a quite a spectacle every summer (and probably rip up the satellite fleet), but it has not happened (although I did not check the historical records for the years after this date). If it did happen for a few years afterwards, surely the event would have been noted.

Re:Where's the meteor shower? (0)

Anonymous Coward | more than 2 years ago | (#37749776)

Um...not every comet comes by once a year? Haileys takes 87 years, and is considered a short term comet. Long term comets take hudreds or thousands of years. Given we know nothing about this comet except a report by one guy from 1883, kind of hard to know when, or even if, it will come back.

Re:Where's the meteor shower? (1)

Chris Burke (6130) | more than 2 years ago | (#37750412)

Um...not every comet comes by once a year?

The comet doesn't have to come by once a year in order to produce an annual meteor shower. The shower is caused by the earth passing through the trail of debris left in the comet's orbit. For instance the famous Leonids are created by a comet with a 33 year orbit around the sun.

Re:Where's the meteor shower? (1)

mikael (484) | more than 2 years ago | (#37752136)

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.

Oh no! (0)

Anonymous Coward | more than 2 years ago | (#37749252)

Space Nutters will lose one of their core beliefs, that a comet/asteroid/alien invasion will destroy the Earth and therefore we must leave it!

Not so fast? (1)

Anonymous Coward | more than 2 years ago | (#37749470)

Comet Nearly Hit Earth? Not So Fast

OK, as you wish:

Coooommmmehhhhhht Neeeeeeaaaaarrrrrllllllyyyyy Hiiiiiiiit Eeeeeaaaaarrrrrrrth?...

Shoemaker-Levy 9 (0)

Anonymous Coward | more than 2 years ago | (#37749596)

Not trying to gainsay the conclusion, the alleged event does seem pretty unlikely. But there is counter-evidence to one of Plait's statements: "When comets break up, they spread out." Shoemaker-Levy 9 exhibited very linear breakup pattern. Another comet with this pattern could plausibly have a close encounter, yet have all of the major components miss impacting.

Still doesn't account for small particles & gasses, lack of corroborative observations, lack of such a comet being observed since then, etc...

Story doesn't add up (1)

BMOC (2478408) | more than 2 years ago | (#37749624)

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 crossed the comet's orbit during the time of the transit, which would mean impact I should think. The story just doesn't add up.

Re:Story doesn't add up (1)

Antisyzygy (1495469) | more than 2 years ago | (#37750422)

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:Story doesn't add up (1)

Anonymous Coward | more than 2 years ago | (#37751964)

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].

Re:Story doesn't add up (1)

emaname (1014225) | more than 2 years ago | (#37750766)

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.

Well, in fairness... (1)

Zooperman (1182761) | more than 2 years ago | (#37749722)

... 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.

For the record (1)

KingofSpades (874684) | more than 2 years ago | (#37749798)

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]

Re:For the record (1)

demonbug (309515) | more than 2 years ago | (#37750864)

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 on an impartial basis and appearance of a paper is not intended in any way to convey tacit approval of its assumptions, methods, or conclusions by any agent (electronic, mechanical, or other). We reserve the right to reject any inappropriate submissions. (Emphasis added)

So, until this actually appears in a journal it might be a bit premature for those of us not in the field to be discussing it (and some of the issues pointed out in Bad Astronomer and elsewhere probably mean that it won't be getting published, at least in the current form).

Aren't we missing something? (1)

Nox3173 (1495587) | more than 2 years ago | (#37749896)

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.

Re:Aren't we missing something? (1)

Antisyzygy (1495469) | more than 2 years ago | (#37750400)

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:Aren't we missing something? (1)

k6mfw (1182893) | more than 2 years ago | (#37751460)

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."

There's 1 thing I hate about Phil's BA blog... (1)

Maow (620678) | more than 2 years ago | (#37751720)

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, it wouldn't be half as bad. /rant

Thanks Phil, I truly do like your blog.

Re: (0)

Anonymous Coward | more than 2 years ago | (#37751746)

Krakatoa? A bit far from the observation site but..?

Puh (0)

Anonymous Coward | more than 2 years ago | (#37752510)

Screw Phil - that guy gets on my nerves!

Rules. (1)

databaseadmin (1978316) | more than 2 years ago | (#37779866)

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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