Unknown 7m Asteroid Almost Impacted Earth 289
xp65 writes "A previously undiscovered asteroid came within 14,000 km of Earth — just over one Earth diameter, 1/30 the lunar distance — on Friday, and astronomers noticed it only 15 hours before closest approach. On Nov. 6 at around 16:30 EST, a 7-meter asteroid, now called 2009 VA, came only about 2 Earth radii from
impacting our planet. This is the third-closest known non-impacting Earth approach on record for a cataloged asteroid. The asteroid was discovered by the Catalina Sky Survey and was quickly identified by the Minor Planet Center in Cambridge MA as an object that would soon pass very close to the Earth. JPL's Near-Earth Object Program Office also computed an orbit solution for this object, and determined that it was not headed for an
impact." The article notes, "On average, objects the size of 2009 VA pass this close about twice per year and impact Earth about once every 5 years."
OH NOES!!! (Score:2)
Comment removed (Score:4, Interesting)
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This seems like a nonsensical conclusion -- larger objects are easier to detect, both by virtue of being larger and, since they are a potential threat, are more worthy of attention and effort.
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Re:OH NOES!!! (Score:5, Insightful)
This does not indicate a question of looking in the right direction. Seeing something that small is basically impossible until its right on top of us even if you're looking straight at it, which is fortunate since its not a big concern. Compare a 7 meter asteroid with a 300 meter asteroid such as 99942 Apophis:
Since surface projection is proportional to the radius squared, Apophis is likely to be 100,000 times brighter, or around 12.5 stellar magnitudes. During the 2029 close approach, when Apophis will be within the geostationary belt, it will be magnitude 3.3, meaning that a 7-meter asteroid would be around magnitude 16. This is below the limiting magnitude of most telescopes being used in these searches, so only the very large (1+ meter) would be able to find it even when that close.
Also, there are a number of individuals doing this in addition to the official NASA work. This was processed through the Minor Planet Center in Cambridge, to which it is quite easy to submit information on new asteroids. With automated amateur equipment (the well-funded 60 year old amateur, not the $200 14 year old amateur) its quite easy to set up a system to automatically observe a region of sky and detect asteroids. If you have a series of plates indicating an asteroid, they can be submitted to the MPC through automated software and its all logged. You may not be satisfied, but its certainly not nothing, even if the NASA effort itself is underfunded.
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Apophis is likely to be 100,000 times brighter
(300 / 7)^2 = about 1,800, which is not very close to 100,000
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You're right. I accidentally typed in (300*300/7*7) instead of (.../(7*7)). Mea culpa.
At any rate, its around 10 stellar magnitude off, which means it would be around magnitude 14 on a very near approach. This is just barely visibile in a 16" telescope, so its still very hard to see.
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As a comparison for the non-astronomers:
In college, we had a pretty sweet 0.8m diameter scope. The limiting resolution of that was about 12 magnitude. Magnitude goes up as powers of ten. So 16th magnitude would be 10^4 times dimmer than what we could see with that scope. Even a 1m scope would have issues with that. You'd need fantastic conditions and very, very good mechanics to be able to take exposures long enough to reliably capture 16 magnitude.
Take into account that we can only reliably
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We track 90% of the near-earth objects that have a possibility of causing global catastrophe. While there's certainly room for improvement, we've actually been doing quite a lot of looking.
To give a sense of scale, global-catastrophic asteroids are 1 km in diameter; this one was 7 m.
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Isn't it more likely that number was just made up to give a false sense of security?
Knowing NASA, no. Is there some component of your argument that isn't just baseless speculation?
This site is better, by the way: http://neo.jpl.nasa.gov/ [nasa.gov]
Re:OH NOES!!! (Score:5, Insightful)
Because we don't actually know we're tracking 90% of NEOs. We estimate that we're tracking 90% of them. We can't actually know we're tracking them, because we simply haven't discovered them all. (comparatively) tiny objects in a slow orbit that may cross our own orbit at some point in the future, but that are so dark that they're black, and so cold they're hard to tell from the ambient radiation on the infrared and other bands? The unfortunate reality is that we just can't see some of what's out there, either because we haven't looked in the right part of space with the right equipment, or because the right equipment doesn't exist.
We figure we're probably tracking about 90%, based on our estimates of the mass of the solar system and how much of what we're actually tracking. We could be tracking 100% of the stuff that actually poses a threat. We could be tracking 50% of it. But the best guess we actually have is that we're somewhere around 90% at the moment, and that the number will go up over time. But we still might never see the one that wipes us out.
Perhaps a better question is: if we can detect the one that's about to hit us, are we likely to be able to do anything about it?
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If we know we're tracking 90% of NEOs, why not the other 10%? Isn't it more likely that number was just made up to give a false sense of security?
OMG, CONSPIRAZY!!!1!1!!ELEVEN!!
You don't get your search-for-planet-smashers budget increased by underestimating the number of objects out there - if NASA were going to start pulling figures out of their collective asses, they'd overestimate. Luckily, though, we have this thing called "science" which means that such estimates are generally derived using the best available data, and the results are published so that others can review the methodology and confirm or challenge the results. The estimates which
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Although, to be fair, even if we did spot one, it's not like we can jump out of the way or anything.
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To quote Billy Bob Thornton in the movie Armageddon:
Well, our object collision budget's a million dollars. That allows us to track about 3% of the sky, and beg'n your pardon sir, but it's a big-ass sky
Re:OH NOES!!! (Score:5, Funny)
Womprat = 2m
Asteroid = 7m
If by not much bigger you mean nearly triple the size... then yes. It's not much bigger.
this has been you Star Wars nitpick of the day. Thank you.
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"Much" is a relative term. When your point of comparison is a space station the size of a small moon, 10m isn't "much" bigger than 2m.
Fear the rodents of unusual size... :P (assuming a womprat is a rodent...)
we didn't see it (Score:2)
what if we didn't see a 20m asteroid? how about a 100m asteroid? this 7m one makes us think about those possibilities as a completely valid concern
fear mongering is a big problem in this world. but the antidote to fear mongering is NOT complete imperviousness to fear. that's just as idiotic as fearmongering. what you need is balance between panty twisting hysteria and unresponsive inertia
fear is a healthy emotion. it keeps you alive. its a valid motivation, when combined with intelligence
so the proper respo
wah! (Score:5, Funny)
Tracking/Routing number? (Score:2, Funny)
Dang! It's the third time they try to ship my package and miss; I've had enough... And so much for the "confidential" packaging!
Hardly noticeable if it impacted (Score:5, Informative)
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It would sound much more sinister and dangerous if they start reporting these sizes in feet and inches. :)
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It would sound much more sinister and dangerous if they start reporting these sizes in feet and inches. :)
...and its mass in stone.
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Hehe - that may work the other way around...everyone would be so confused to the extent that we just shrug off the danger and stop stressing out about things that "almost" kill us all on a daily basis.
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I was about to say - missing a 7 meter asteroid passing at that distance is roughly akin to missing a pea in the middle of the highway you're currently doing 60MPH down. In rush hour traffic.
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Well, actually, missing a 7 meter asteroid passing at this distance is exactly akin to missing just about anything in the middle of the highway. Even another 7m asteroid.
Re:Hardly noticeable if it impacted (Score:5, Funny)
Thank you for the car analogy. Without it, I would have been totally incapable of understanding the situation.
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I have trouble believing that people wouldn't at least hear it, even if it popped, as the estimate says, at 121,000 feet.
That is 24 miles away, vertically, through "atmosphere" that qualifies as a pretty decent vacuum.
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The airburst would unleash about 130 tons on TNT [arizona.edu], about 10 times the size of the Hiroshima bomb.
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Distance from Impact: 1.00 km
Projectile Diameter: 70.00 m (10x the size of our rock)
Projectile Density: 3000 kg/m3 (dense rock)
Impact Velocity: 45.00 km/s
Impact Angle: 45 degrees
Target Density: 2500 kg/m3
Target Type: Sedimentary Rock
------
The project
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The asteroid is quite unlikely to unleash any trinitrotolulene.
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The airburst would unleash about 130 tons on TNT [arizona.edu], about 10 times the size of the Hiroshima bomb.
What and the who now? Little Boy was 13+ KILO tons. That's 1,300 tons. That puts your asteroid impact at one third the blast, meaning you're off by a factor of 100.
Re:Hardly noticeable if it impacted (Score:5, Funny)
This is unimportant (Score:2)
If the threat were 7m asteriods, no one would be monitoring. We'd certainly not be talking about the possibility of mass extinction. Yes some people might die, just as some people die every day. The reason to monitor near earth asteroids is the big ones that can kill off most of the life on our planet in a very short period.
You are all missing the *real* point... (Score:5, Funny)
Car Analogy? (Score:2)
I think I need a car analogy to fully understand this story.
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Say you're a new galactic overlord driving a car, but you're in space, and you're drunk. You see this big blue planet getting bigger and bigger in your windscreen. At the last possible moment, you hear me yelling to get the hell off my lawn, you suddenly swerve, and miss. But you've ruined Cowboy Neal's tulips, you insensitive clod!
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Oh, and PS: This happens twice a year. And about every five years, you don't swerve fast enough.
(this is the "hauling a trailer" part of the car analogy).
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An asteroid about the size of a large pickup truck. Does that work?
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Space is getting OLD (Score:2)
Pssh. 7 meters? Come on outer space, for all your terrifying voidsomeness you sure aren't flinging much in the way of horror our way. What's this I heard apparently Apophis now isn't even a threat. And the Tunguska incident? Hate to break it to your outer space, but nobody was living int he area you hit. Yeah and you'll probably point out the dinosaurs. Sure sure. Let's see you land a decent hit a little more often then every few million years.
What's wrong outer space? Having trouble hitting a mote of dust
The kind I want to hit Earth (Score:2)
Re:How Much Damage? (Score:5, Funny)
Anybody want to weigh in?
You expect nerds and geeks to give their actual weight online?!
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74 kg. Sorry, don't have it in pounds. ;)
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Re:How Much Damage? (Score:4, Interesting)
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The article doesn't say what level of damage would have resulted from an impact. Anybody want to weigh in?
I remember my old science book said that the one responsible for Meteor Crater was the size of a box car but that's kind of imprecise. It's a question of mass and velocity. The looser, rock-ice bodies tend to explode in the air. We've had a couple historically that were big enough to be mistaken for nuclear tests but they exploded high in the air over remote stretches of ocean.
Re:How Much Damage? (Score:5, Informative)
Asteroid Impact Calculator [arizona.edu]. Handy thing to have bookmarked, in the event that the astronomers see the next one from far enough off.
It's impossible to be sure what the density and angle of incidence would have been in this case, as this sort of data isn't usually published. It's also impossible to be sure of composition, as that depends on where the asteroid was from. Thus, any results you DO get from the calculator are either meaningless (too much garbage in) or extreme values only.
Having said that, such calculators are fun when they find truly massive craters. The crater under the antarctic ice, for example, is so large that the Earth was unlikely to have ever been hit by something that big in the past 4 billion years. Antarctica is very modern, in comparison.
Re:How Much Damage? (Score:5, Funny)
Handy thing to have bookmarked
Sounds like a good thing to ping every so often. If the latency goes up or it stops responding altogether then the chances are that a whole load of people somewhere know something that you don't.
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They really needed it 250-300 million years ago [universetoday.com] though. Tweaking the impact velocity to get roughly the right values according to the article, the calculator reveals anyone on the edge of the crater would be vaporized [arizona.edu], ripped to shreds from the pressure wave, then pulverized by the earthquake and drowned by a subsequent tsunami.
Now, THAT is what I call having a bad day.
Re:How Much Damage? (Score:5, Insightful)
Since it claims objects that size impact Earth about once every 5 years, the damage would be the same that we see every time one of these impacts. If you can't think of the last time that happened or you can't think of a damage report about that, then that should be your answer.
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a 7 meter object has less than a third of the mass of a 10 meter object. And some of that mass would be lost to ablation on atmospheric entry. Depending on a number of factors the damage would likely be somewhere between a very large conventional bomb and no damage at all.
Re:How Much Damage? (Score:5, Insightful)
Re:How Much Damage? (Score:5, Informative)
According to this (I didn't verify any facts) - http://wiki.answers.com/Q/How_much_of_the_Earths_surface_is_inhabited_by_humans [answers.com]
About 1% of the surface is inhabited. So, an impact should directly affect people about once every 500 years. Maybe it's the next time?
Re:How Much Damage? (Score:4, Interesting)
From Wikipedia [wikipedia.org]:
If it hit near the center of a large city it could really suck; however, most of the earth's surface is covered by water, desert, mountains, or rural areas, and thus most asteroid impacts of this size do not cause massive loss of life.
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Re:How Much Damage? (Score:5, Informative)
Re:How Much Damage? (Score:4, Insightful)
Regardless, a post farther down links to an impact calculator that claims it bursts in mid-air and results in no significant impact, so this speculation is moot (I am assuming the calculator is well-written).
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It's 30 percent less diameter. .7 cubed means 1/3 the mass.
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Re:How Much Damage? (Score:4, Informative)
What about tsunamis?
Well, other posters have established (well, speculated) that the impact energy would be significantly less than the Hiroshima bomb... there's a link elsewhere in this thread which discusses that a meteorite with a diameter of 10m on impact (meaning significantly larger than 10m when it entered the atmosphere) would have about the explosive force of the Hiroshima bomb.... The number that people are throwing around seems to be around 30-35% of the impact energy, if it hit the ground with a diameter of 7m. I'm going to have to rely on other peoples' calculations, but it does seem to be supported by others.
Let's assume 33%, because the math's easy. The Hiroshima bomb exploded with a peak force of about 18kt, according to Wikipedia. 1/3 of that is 6kt. This is an important number... by any account, it's a big explosion. The largest conventional explosive currently in use in the world is the US-built Massive Ordnance Penetrator (MOP) with a blast yield of 13.6 tonnes... we're talking 400 times more explosive force. If it hit a city with that kind of force, it would do extensive damage.
But let's put this in perspective, and actually answer your question: On May 5, 1954, the US Navy set off Castle Yankee, part of the Operation Castle set of nuclear weapons tests, on the surface of the ocean off Bikini Atoll in Micronesia. The yield of this bomb was 13.5mt, more than 2000x more powerful than this meteorite could possibly be, even assuming that it did not shed any mass at all during entry. Castle Yankee did not cause a tsunami. The likelihood of such a meteorite causing a tsunami is slim to nil.
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That is, unless your name is either Bambi or Nemo...
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An impact by an object in this size range [around 10m] would correspond to an impact energy roughly comparable to the Hiroshima bomb, if the object had hit the Earth's surface.
Except that it is highly unlikely that any such asteroid would survive sufficiently intact to impact the earth with its full energy.
A far more likely scenario is that the object would cause an air blast high in the atmosphere and a few small, surviving fragments would pelt the earth here and there. Even a blast equivalent to Little Boy which occurred in the upper atmosphere would be barely noticeable on the ground, thanks to the 1/r^2 effect of a spherical blast, the absorption of energy by the atmosphe
Re:How Much Damage? (Score:5, Informative)
It would most likely bursts into a cloud of fragments at an altitude of 8980 meters. Minor local damage might occur if a larger fragment happens to hit a house.
http://www.lpl.arizona.edu/impacteffects/cgi-bin/crater.cgi?dist=0.001&diam=7&pdens=&pdens_select=8000&vel=17&theta=45&tdens=2500&tdens_select=0 [arizona.edu]
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Minor local damage??? It's a 400 kiloton equivalent airburst energy...
It will do 1 PSI overpressure (broken windows, etc) about 13 kilometers away from ground center point of explosion.
Right under the explosion, it will do about 2.5 PSI overpressure, and collapse relatively weak residential structures.
That energy level is going to kill people, if it's over inhabited areas. Not a lot of people - many or most directly under it would survive that overpressure level - but it will collapse things, and of a few
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As a nitpick, that's actually 40 kiloton equivalent (0.40 x 10^-1 megatons = 0.04 megatons = 40 kilotons). You don't get a 400 kiloton airburst until you go up to 15m diameter [arizona.edu]
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40 Kiloton, 40. Not 400.
8980 meters, eh? (Score:5, Funny)
It would most likely bursts into a cloud of fragments at an altitude of 8980 meters. Minor local damage might occur if a larger fragment happens to hit a house.
http://www.lpl.arizona.edu/impacteffects/cgi-bin/crater.cgi?dist=0.001&diam=7&pdens=&pdens_select=8000&vel=17&theta=45&tdens=2500&tdens_select=0 [arizona.edu]
Thanks for not rounding that off to "nine kilometers" or even "about 10 km" as some less mathematically-inclined contributors would have done. If you've laboriously and precisely calculated that 2009 AV is exactly 7.000 meters in diameter, has a density of 8.000 g/cm3 and will hit the atmosphere at a 45.00 degree angle at exactly 17.00 km/s, why give up that hard-earned precision in your result?
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why give up that hard-earned precision in your result?
Because he doesn't know your height above sea level, other than its within -500 feet or so, to about 29000 feet or so?
"The projectile bursts into a cloud of fragments at an altitude of 8980 meters = 29500 ft"
Assuming it blew up directly over your head, that would really suck if you just climbed to the top of Mt Everest at 29029 and the final detonation was a mere 471 feet over your head.
On the other hand, my house at around 900 feet ASL would be about 6 miles away from the final explosion.
Folks in Denver "m
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Re:How Much Damage? (Score:5, Informative)
Result = no strike (Score:3, Interesting)
I shoved some numbers in, making it quite dense with the recommended average velocity for an asteroid, impact angle etc and got the following results:
Your Inputs:
Distance from Impact: 1.00 km = 0.62 miles
Projectile Diameter: 7.00 m = 22.96 ft = 0.00 miles
Projectile Density: 3000 kg/m3
Impact Velocity: 17.00 km/s = 10.56 miles/s
Impact Angle: 45 degrees
Target Density: 2500 kg/m3
Target Type: Sedimentary Rock
Energy:
Energy before atmospheric entry: 7.79 x 1013 Joules = 0.19 x 10^-1 MegaTons TNT
The average interva
Re:How Much Damage? (Score:4, Funny)
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... whatever's left would be no bigger than a chihuahua's head.
So you're saying it would be as annoying? Guess Earth would survive...
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....no bigger than a chihuahua's head.
I am interested in your unit and measurement system and would like to adopt it for my country. Could you please calculate the conversion factor from chihuahua heads to Sydharbs [wikipedia.org] and Elephants [wikipedia.org]
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Or 0.0000853 AU.
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The article doesn't say what level of damage would have resulted from an impact.
Depends. Is there a modifier for a sneak attack?
Re:How Much Damage? (Score:5, Funny)
Depends. Is there a modifier for a sneak attack?
yeah, +3 HOLY SHIT A FUCKING METEOR!
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Re:How Much Damage? Not much! (Score:4, Informative)
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Unless it lands on your house!
Re:How Much Damage? (Score:5, Funny)
Re:How Much Damage? (Score:5, Funny)
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The real question is would it impact at all.
How much would burn up after breaking up in the atmosphere.
If one of these impacts every 5 years, and 65% of the earth's surface is water, you would expect 1 of every 3 or 4 to land on dry land, so in 20 years we should have had some impacts in places they can be found.
Since no one here can remember the last one, you have to assume the damage has been minimal.
Re:LHC (Score:5, Funny)
Are you kidding? That thing can't even stand up to a bird with a bagel.
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At this point I think throwing it at the asteroids might be a more cost-effective solution.
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Because (to quote Calvin): Verbing weirds language.
Re:"Impact" Earth? (Score:5, Informative)
Hmmm... well, I realize that checking a dictionary first would've been a lot of work, but here's what m-w has to say about it [merriam-webster.com]. Note that the first entry is for the verb "impact".
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Other words in m-w:
lite
homie
ain't
irregardless
lol
conversate
phat
wigger
gaydar
My point being that m-w is a descriptive rather than prescriptive dictionary. It's a dictionary for figuring out what a word means in popular (or unpopular) use rather than figuring out whether a word is the *right* word according to scholastic tradition.
Choose your side, but impact (v) makes my teeth grind in the same way that gift (v) does.
-b
Self-gooooooooaaaaaaal! (Score:3, Informative)
(If the link breaks, the book is Merriam-Webster's dictionary of English usage)
The link is not broken, and here are two snippets that jumped right out at me:
"But since part of the criticism seems to be based on the erroneous notion that that the verb is derived from the noun based on functional shift, we must first pursue a little "
and
"But impact was a verb in English before it was a noun."
and
"This is not a case of a verb derived from an earlier noun."
In summary:
While impact as a verb has been around for a
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Hey, to be fair, it was kdawson who added the part which basically says "By the way, this was no big deal".
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Easy there, Superman. I know you're hard up for publicity these days, but we didn't really need you to stop this one.