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Billion-Ton Comet May Have Missed Earth by a Few Hundred Kilometers in 1883

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Re: Billion-Ton Comet May Have Missed Earth by a Few Hundred Kilometers in 1883

#31

Post by rorrr »

rizzom5000 wrote: post #26
AlexMennen wrote: post #20

Earlier quoted context omitted.

If there is a significant chance that a comet will hit and destroy us, it makes sense to do everything we can to prevent it from doing so. Given the stakes, .1% chance should be more than enough for us to take it seriously. It does not seem plausible that we could harm ourselves much by nuking a comet that wasn't going to hit us anyway.

It does seem plausible that we could in fact harm ourselves by attempting to launch a nuclear device out of Earth's orbit. We do have a record of failed launches, several of them recent. Once the nuclear device is out of orbit however, I agree that the harm it can do to us is negligible. Edit: Also, it just occurred to me the possibility of deflecting a comet (which was never in our path) into our path, instead of aw…

If a billion-ton comet is about to hit our planet, a failed attempt to launch a nuke doesn't matter in the slightest.

Re: Billion-Ton Comet May Have Missed Earth by a Few Hundred Kilometers in 1883

#32

Post by [deleted] »

rorrr wrote: post #31
rizzom5000 wrote: post #26

Earlier quoted context omitted.

It does seem plausible that we could in fact harm ourselves by attempting to launch a nuclear device out of Earth's orbit. We do have a record of failed launches, several of them recent. Once the nuclear device is out of orbit however, I agree that the harm it can do to us is negligible. Edit: Also, it just occurred to me the possibility of deflecting a comet (which was never in our path) into our path, instead of aw…

If a billion-ton comet is about to hit our planet, a failed attempt to launch a nuke doesn't matter in the slightest.

[deleted]

Re: Billion-Ton Comet May Have Missed Earth by a Few Hundred Kilometers in 1883

#33

Post by ChuckMcM »

jacquesm wrote: post #22
ChuckMcM wrote: post #12

Earlier quoted context omitted.

Was going to add this one as well. A comet of that size, that close, would have raised questions in other places. The point that we didn't have nearly the observational capacity a couple of hundred years ago that we have today is well made, we certainly might have dodged a bullet, we have seen two comments hit the bigger planets (Jupiter and Saturn) but we only noticed because we were looking. So I share the skeptici…

They got a lot closer than that in recent times, but not quite as massive: http://en.wikipedia.org/wiki/Tunguska_event In the long run cometary impact is pretty much a certainty and close passes are a lot more likely than impact. So even if this particular observation is probably attributable to something else there is a good chance that something like it did happen at another point in time in the last 2,000 years or…

There is a really interesting question which I posed to the NASA near earth team at one of their talks at Ames which was "what sort of evidence would an intra-atmospheric near miss produce?" Which is to say a comet that missed by 50,000 to 125,000' rather than further out. The speculation is that it would result in wide spread fires (the compressive heating of the air in front of it would ignite things). Basically it could transfer a lot of energy to the atmosphere. But most felt that a comet that close would be in pieces and at least some of it would leave a crater trail.

Re: Billion-Ton Comet May Have Missed Earth by a Few Hundred Kilometers in 1883

#34

Post by mserdarsanli »

venus wrote: post #5

> A sobering thought. An even more sobering thought is that even in the present day, if we detected something like that heading our way, there'd be absolutely nothing we could but sit and wait for it to arrive.

Well, there are actually people working to save the Earth literally. http://b612foundation.org/

Re: Billion-Ton Comet May Have Missed Earth by a Few Hundred Kilometers in 1883

#35

Post by lutusp »

A quote: "They point out that nobody else on the planet seems to have seen this comet passing in front of the Sun, even though the nearest observatories in those days were just a few hundred kilometers away. That can be explained using parallax."

It can also be explained by the simple fact that (a) not many observatories specialize in observing the sun even now, and (b) the observation may only have lasted a few hours (as with this year's Venus transit). Remember Occam's razor -- the simplest explanation is to be preferred.

Re: Billion-Ton Comet May Have Missed Earth by a Few Hundred Kilometers in 1883

#36

Post by lutusp »

Gustomaximus wrote: post #3
dmix wrote: post #2

> They point out that nobody else on the planet seems to have seen this comet passing in front of the Sun, even though the nearest observatories in those days were just a few hundred kilometers away. This is 1883 and noone else recorded seeing it? Even in all of mexico?

The do say in the article about no-one seeing it; "That can be explained using parallax. If the fragments were close to Earth, parallax would have ensured that they would not have been in line with the Sun even for observers nearby. And since Mexico is at the same latitude as the Sahara, northern India and south-east Asia, it's not hard to imagine that nobody else was looking." Is this realistic? Also would the time…

> The do say in the article about no-one seeing it; "That can be explained using parallax ..."

> Is this realistic?

No. Even today not many observatories specialize in sun observations. It's not at all surprising that only one astronomer witnessed this, and it's a stretch to suggest the explanation that the observed object was therefore very close -- there are many more plausible explanations.

> Also would the time of day matter?

No, not for an object silhouetted against the sun. Consider this year's Venus transit -- everyone who could see the sun at the appointed time, also could see the transit.

Re: Billion-Ton Comet May Have Missed Earth by a Few Hundred Kilometers in 1883

#37

Post by lutusp »

TimJRobinson wrote: post #13

I'm confused as to why this is coming up now, did they find some new evidence or residual rock from this comet? If not how do they now know that it was actually a comet and not simply a mistake on the astronomers part as they previously thought it was?

> ... how do they now know that it was actually a comet and not simply a mistake on the astronomers part as they previously thought it was?

They don't. The linked article assumes the veracity of the original account, it doesn't introduce anything new.

Re: Billion-Ton Comet May Have Missed Earth by a Few Hundred Kilometers in 1883

#38

Post by berntb »

rizzom5000 wrote: post #26
AlexMennen wrote: post #20

Earlier quoted context omitted.

If there is a significant chance that a comet will hit and destroy us, it makes sense to do everything we can to prevent it from doing so. Given the stakes, .1% chance should be more than enough for us to take it seriously. It does not seem plausible that we could harm ourselves much by nuking a comet that wasn't going to hit us anyway.

It does seem plausible that we could in fact harm ourselves by attempting to launch a nuclear device out of Earth's orbit. We do have a record of failed launches, several of them recent. Once the nuclear device is out of orbit however, I agree that the harm it can do to us is negligible. Edit: Also, it just occurred to me the possibility of deflecting a comet (which was never in our path) into our path, instead of aw…

Nuclear weapons have fallen out of the sky before. No, they won't explode -- it isn't easy to make one go boom.

But I would not be surprised if Green political parties argue that risking a few km^2 contamination is worse than a certain dinosaur killer... :-)

http://en.wikipedia.org/wiki/1966_Palomares_B-52_crash

"The non-nuclear explosives in two of the weapons detonated upon impact with the ground, resulting in the contamination of a 2-square-kilometer (490-acre) (0.78 square mile) area by plutonium. [... another which fell] into the Mediterranean Sea, was recovered intact"

Re: Billion-Ton Comet May Have Missed Earth by a Few Hundred Kilometers in 1883

#39

Post by bad_user »

gnosis wrote: post #25
Shank wrote: post #7

Earlier quoted context omitted.

This is slightly true, though notably the Torino Scale mentions that once an object is classed at level 5, governments may begin to take action to counteract such a collision before it arrives at earth, if the encounter is set to be less than a decade away. http://en.wikipedia.org/wiki/Torino_Scale Edit: NASA's JPL maintains the Sentry Risk Table, which tracks all objects that may impact the Earth, with various data…

The time to initiate an asteroid defense project is long before a threat is even detected. There needs to be time for technology development, deployment, and testing. Tackling an extinction-level event is not something we want to scramble for at the last possible minute, using untried technology.

Research in this area should have happened since yesterday, but deployment and testing?

The probability of something big hitting us is really low, coupled with the fact that we can see it coming since all objects in space are visible. Miss-calculating a trajectory could indeed happen and we may not notice it if it's coming from the direction of our sun, but the probability of that is even lower.

So why would you spend tons of natural resources, time and money for a machinery of dealing with a problem that we may not have in the next 100,000 years? And what should that machinery do in the meantime?

Personally, I think our world has to solve bigger and more imminent problems that can lead to extinction too ... hunger, disease, overpopulation, economic recessions, natural resources running out, global warming, the destruction of the only habitat we know that can sustain life, nuclear wars and the list of things that can happen in the next 400 years can probably go on. Heck, we came closer to extinction during the Cold War than we ever ever did from a comet passing by and the only thing saving us was the few reasonable men in charge, but we may not get so lucky next time.

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