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In that case, we are talking about sentient creatures, in which case difficulty has a different meaning. When we are talking about objects such as comets (unmeddled with), the word difficulty has no meaning apart from in the sense of probability.
Kavekk wrote:
In that case, we are talking about sentient creatures, in which case difficulty has a different meaning. When we are talking about objects such as comets (unmeddled with), the word difficulty has no meaning apart from in the sense of probability.
What the hell are you smoking?
A rock in space could easily hit another rock in space. This does not imply a high probability of it happening.
I think what BD is trying to say is that, though improbable, the chances of a comet colliding with a planet, or being on track to do so, can occur without requirement for special or extenuating circumstances, the possibility exists in the natural order of things, and therefore it could easily happen. IE a comet wouldn't have to be knocked off course, or propelled by martians into the planet, it can do so on it's own by pure random chance.
Edited, Jul 22nd 2009 11:27am by reavenance
Edited, Jul 22nd 2009 11:27am by reavenance
reavenance wrote:
I think what BD is trying to say is that, though improbable, the chances of a comet colliding with a planet, or being on track to do so, can occur without requirement for special or extenuating circumstances, the possibility exists in the natural order of things, and therefore it could easily happen. IE a comet wouldn't have to be knocked off course, or propelled by martians into the planet, it can do so on it's own by pure random chance.
Edited, Jul 22nd 2009 11:27am by reavenance
Edited, Jul 22nd 2009 11:27am by reavenance
That can't be it, because what I said previously* makes perfect sense with that definition, and BD disagreed with it. That can't be what BD means unless we are suggesting that BD is at fault in some place, which, frankly, is crazy talk.
Quote:
Well, if the comet hit Jupiter, it's orbit might very well not come near Earth at any point.
Kavekk wrote:
reavenance wrote:
I think what BD is trying to say is that, though improbable, the chances of a comet colliding with a planet, or being on track to do so, can occur without requirement for special or extenuating circumstances, the possibility exists in the natural order of things, and therefore it could easily happen. IE a comet wouldn't have to be knocked off course, or propelled by martians into the planet, it can do so on it's own by pure random chance.
Edited, Jul 22nd 2009 11:27am by reavenance
Edited, Jul 22nd 2009 11:27am by reavenance
That can't be it, because what I said previously* makes perfect sense with that definition, and BD disagreed with it. That can't be what BD means unless we are suggesting that BD is at fault in some place, which, frankly, is crazy talk.
Quote:
Well, if the comet hit Jupiter, it's orbit might very well not come near Earth at any point.
What you're saying is that if the comet hit Jupiter, then it is unlikely that it would have crossed earth's path. Right? And I'm telling you that your assumption is invalid. There is no data to suggest that simply because something's path takes it close to Jupiter that it is unlikely to come close to earth, especially in relation to comets which are known to generally have very elliptical orbits.
You're assuming a probability based on data that doesn't exist.
What I suspect is that this particular comet, or whatever object it was, does not approach Earth and was not considered a NEO (near earth object) which are religiously tracked and monitored.
Stuff hits other stuff in the solar system all the time, and the reason no one noticed this particular object is because it wasn't important enough to bother with. It IS neat that something hit Jupiter. But it's not the first time, nor will it be the last time, and Jupiter is so very much bigger than Earth that I suspected it happens a lot more frequently than we'd expect. Jupiter also has a much larger gravity well than earth, so it has greater capability of drawing objects toward itself.
The scale for impacts big enough to cause mass extinctions on earth is in millions of years. And unlike the dinosaurs, we have the technology to know when it's coming and possibly do something about it.
Stuff hits other stuff in the solar system all the time, and the reason no one noticed this particular object is because it wasn't important enough to bother with. It IS neat that something hit Jupiter. But it's not the first time, nor will it be the last time, and Jupiter is so very much bigger than Earth that I suspected it happens a lot more frequently than we'd expect. Jupiter also has a much larger gravity well than earth, so it has greater capability of drawing objects toward itself.
The scale for impacts big enough to cause mass extinctions on earth is in millions of years. And unlike the dinosaurs, we have the technology to know when it's coming and possibly do something about it.
The Great BrownDuck wrote:
So, an object large enough to create an earth sized crater smashes into Jupiter, going completely unnoticed until after the impact and it's just "neat"? I realize Jupiter is some 400 million miles from Earth and about 11 times its diameter, but shouldn't we be able to detect something this big before it happens? NASA wasn't even remotely aware of the impact until someone who just happened to be spying Jupiter gave them a heads up. Sounds like our NEO search funding needs a boost.
There are no craters on gas giant planets. The largest fragment from Shoemaker-Levy 9, the fragmented comet that impacted Jupiter back in 1994, was only 2km(1.2mi) across. It left a blemish on Jupiter's atmosphere about 12000km in diameter, about twice that of Earth's. It was traveling close to 60km a second when it impacted.
Because Jupiter has no solid surface (discounting a possible solid core), the only thing an impactor has to impact against is gas. The friction caused by entering the atmosphere caused a fireball that reached nearly 24000K, and was itself thousands of kilometers in diameter. As it plunged into the atmosphere, the fragment's surface vaporized, leaving behind huge amounts of itself at various levels of the atmosphere, not to mention stirring up the juicy lower levels of the atmosphere as well.
Factor in the extreme speed of winds and atmospheric circulation in Jupiter, and it's not hard to see how such a (relatively) small impactor can create such a large impact feature that lasts for months.
If the same cometary fragment were to plummet though Earth's thin atmosphere and strike continental rock, it would create a transient crater about 20km across and 7km deep, with a final complex crater about 31km across and only 1km deep.
Basically, the entire impact energy is expended in one single kaboom when striking a rocky world, but on a gas giant the impact energy is spread out of a much larger area and depth.
As far as our instruments not detecting it, I'm fine with it. This rock or comet was only about 500m across, traveling at 60km/s, and was 5-6AU away from us. Had it been closer, it would have been brighter and much easier to spot.
As for Earth-crossing cometary orbits... Most comets have a highly elliptical orbit that takes them from the outer reaches of the solar system (35+AU) to very close to the sun (.1-.5AU). Luckily, most comets have their orbit highly inclined to the ecliptic, which means that when viewed from above the orbit may look like it would cross Earth's, but when viewed from the side it's easy to see that it comes nowhere close to us. Not to say we've never been impacted by a comet, but the chances of an impact similar impact to the one in the op occuring on Earth is about once every 7,200,000 years.
Edited, Jul 22nd 2009 11:38am by Tzemesce
Jupiter being so massive is very important for life on Earth. It undoubtedly throughout history hoovered up loads of Earth-bound junk. This factor alone may explain why intelligent life seems so rare in our galaxy: it could be that all the others are struck by comets too frequently. On the other hand, numerical simulations of solar systems tend to show solar systems similar to ours forming - and thus there is not much special about Jupiter after all.
We get close calls all the time:
http://wcbstv.com/watercooler/asteroid.close.call.2.950047.html
That one, from March of this year, was about 100 feet across and roughly would have been similar to the one which struck Siberia in 1908. It came within 1/5 of the distance to the moon, which is very, very close. It was only spotted 2 days in advance.
We know of stuff that will come within 1% of the distance from the Earth to the Moon:
http://www.universetoday.com/2006/12/27/close-call-with-asteroid-2006-xg1-in-2041/
...but that one is much, much larger and that pass will not occur for about 30 years.
So on the whole, NEO funding is probably roughly appropriate now that science funding is beginning to recover from the worst budget in decades.
We get close calls all the time:
http://wcbstv.com/watercooler/asteroid.close.call.2.950047.html
That one, from March of this year, was about 100 feet across and roughly would have been similar to the one which struck Siberia in 1908. It came within 1/5 of the distance to the moon, which is very, very close. It was only spotted 2 days in advance.
We know of stuff that will come within 1% of the distance from the Earth to the Moon:
http://www.universetoday.com/2006/12/27/close-call-with-asteroid-2006-xg1-in-2041/
...but that one is much, much larger and that pass will not occur for about 30 years.
So on the whole, NEO funding is probably roughly appropriate now that science funding is beginning to recover from the worst budget in decades.
****, I just realised I said "it's" instead of "its". The internet is eating my brain.
Also, there's been a pretty large misunderstanding here.
Most comets do not come close to the Earth. Close does not mean crossing the Earth's orbit, by the way (I'm talking about PHOs, in case you forgot). There are very few comets that are classified as coming dangerously close to the Earth - under a hundred iirc. The Earth does not get hit by comets often. BTW, I'm not saying that it's unlikely because it crosses Jupiter's orbit but that it crossing Jupiter's orbit (and hitting the planet) does not imply that it was a potential threat to the Earth that we missed.
Also, there's been a pretty large misunderstanding here.
Most comets do not come close to the Earth. Close does not mean crossing the Earth's orbit, by the way (I'm talking about PHOs, in case you forgot). There are very few comets that are classified as coming dangerously close to the Earth - under a hundred iirc. The Earth does not get hit by comets often. BTW, I'm not saying that it's unlikely because it crosses Jupiter's orbit but that it crossing Jupiter's orbit (and hitting the planet) does not imply that it was a potential threat to the Earth that we missed.
Kavekk wrote:
@#%^, I just realised I said "it's" instead of "its". The internet is eating my brain.
Also, there's been a pretty large misunderstanding here.
Most comets do not come close to the Earth. Close does not mean crossing the Earth's orbit, by the way (I'm talking about PHOs, in case you forgot). There are very few comets that are classified as coming dangerously close to the Earth - under a hundred iirc. The Earth does not get hit by comets often. BTW, I'm not saying that it's unlikely because it crosses Jupiter's orbit but that it crossing Jupiter's orbit (and hitting the planet) does not imply that it was a potential threat to the Earth that we missed.
Also, there's been a pretty large misunderstanding here.
Most comets do not come close to the Earth. Close does not mean crossing the Earth's orbit, by the way (I'm talking about PHOs, in case you forgot). There are very few comets that are classified as coming dangerously close to the Earth - under a hundred iirc. The Earth does not get hit by comets often. BTW, I'm not saying that it's unlikely because it crosses Jupiter's orbit but that it crossing Jupiter's orbit (and hitting the planet) does not imply that it was a potential threat to the Earth that we missed.
Fair enough. All I'm saying is that I find it weird that an object that caused such a large impact area was completely unnoticed prior to the impact. I definitely fall into the crowd that believes we should have a better map of our own backyard, so to speak. That may not be everyone else's priority, but hey, we can't all focus on the same thing.
The Great BrownDuck wrote:
All I'm saying is that I find it weird that an object that caused such a large impact area was completely unnoticed prior to the impact.
The object was only 500m or so in diameter. It's difficult to spot objects that small at 1AU, let alone 5AU or more.
What you're saying is that if the comet hit Jupiter, then it is unlikely that it would have crossed earth's path. Right? And I'm telling you that your assumption is invalid. There is no data to suggest that simply because something's path takes it close to Jupiter that it is unlikely to come close to earth
Sort of depends where Jupiter and Earth are, no? They move; were you aware of that? Here's the good part, though, we know where they're going to be at any given time fairly accurately! Because of this, there is, indeed, data that demonstrates conclusively that an object in an orbit to bring into contact with Jupiter now was about as likely to cross Earth's path, ever, as a raindrop in Hong Kong is to rape your sister.
Disclaimer:
To make a long story short, I don't take any responsibility for anything I post here. It's not news, it's not truth, it's not serious. It's parody. It's satire. It's bitter. It's angsty. Your mother's a *****. You like to jack off dogs. That's right, you heard me. You like to grab that dog by the bone and rub it like a ski pole. Your dad? Gay. Your priest? Straight. **** off and let me post. It's not true, it's all in good fun. Now go away.
To make a long story short, I don't take any responsibility for anything I post here. It's not news, it's not truth, it's not serious. It's parody. It's satire. It's bitter. It's angsty. Your mother's a *****. You like to jack off dogs. That's right, you heard me. You like to grab that dog by the bone and rub it like a ski pole. Your dad? Gay. Your priest? Straight. **** off and let me post. It's not true, it's all in good fun. Now go away.
Smasharoo wrote:
What you're saying is that if the comet hit Jupiter, then it is unlikely that it would have crossed earth's path. Right? And I'm telling you that your assumption is invalid. There is no data to suggest that simply because something's path takes it close to Jupiter that it is unlikely to come close to earth
Sort of depends where Jupiter and Earth are, no? They move; were you aware of that? Here's the good part, though, we know where they're going to be at any given time fairly accurately! Because of this, there is, indeed, data that demonstrates conclusively that an object in an orbit to bring into contact with Jupiter now was about as likely to cross Earth's path, ever, as a raindrop in Hong Kong is to rape your sister.
I'm ever vigilant on rainy trips to Hong Kong.
This made me rewatch 2001 & 2010 again.
I await Jupiter's impending transformation into a star via monolith any day now.
I await Jupiter's impending transformation into a star via monolith any day now.
"The Rich are there to take all of the money & pay none of the taxes, the middle class is there to do all the work and pay all the taxes, and the poor are there to scare the crap out of the middle class." -George Carlin
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