I heard about one a year or two ago that a couple of days later was revised to say that it wouldn’t come anywhere near us.
However, someone mentioned to me in the past couple of days that he had heard in the past month that another such similar encounter was projected (in about 30 years) for some other asteroid, but would be VERY close. His source was not the Weekly World News, although I don’t recall what it was.
Did anyone else hear anything else recently?
Yes, I remember that. There was a hullaballoo about it for a few days until another astronomer checked over the numbers again and determined that the asteroid would pass at a safe distance.
I’m sorry I don’t have a cite for you on this.
Zev Steinhardt
Depends on what you mean by “close.” The asteroid predicted in 30 years will pass within (I think) thirty million miles or so from earth. No impact is imminent, according to what I saw on PBS a couple of nights ago. However, there could be a big one out there somewhere that we haven’t seen yet. Scientists can only monitor small portions of the sky at once, and it could be that we just haven’t spotted our doom yet. Who knows? Maybe there’s one inbound at this moment, but they haven’t told us to avoid panic.
Check out pbs.org and the discovery channel web site for more info.
from http://www.skypub.com/news/news.shtml
There is the possibility that this object is actually something launched from Earth, perhaps the third stage of an Apollo mission.
It doesn’t say so at that site, but the chance of it hitting Earth on its subsequent orbit (around 2060) is non-zero (I don’t remember the number).
I’d like to correct a common misperception about the calculations of how close these rocks are going to come.
There is often an announcement that there is a 1-in-X chance that it will hit the Earth. Then a few days later, there will be another announcement that the chance is really 1-in-Y. People usually assume that the first figures were in error because of a mathematical mistake.
That’s not the way it happens. The first figures are the best they can come up with with the data available. They’ve checked their calculations over several times and there aren’t likely to be errors in them.
What allows the revision in the probabilities is additional data. The longer an object is tracked, the better an orbit can be calculated for it. The easiest way to extend the the observational time is to find prediscovery images. That is, finding the object in an image taken for some other purpose. That’s what happened here.
Sorry Lissa but the asteroid will get a lot closer than 30 million miles. More like 258,000 miles which is nearly inside the orbit of the moon and the earth (approx. 250,000 miles earth-to-moon).
Object AN10 will be on its closest approach (1.04 lunar distance) on August 7, 2027. It is around 1 kilometer in diameter.
Object XF11 (maybe the other on asked about in the OP?) is due to approach within 2.52 lunar distances on October 26, 2028. XF11 is around 2 kilometers in diameter.
(Source: http://www.nearearthobjects.co.uk/neo_report.cfm?Mode=Synopsis&ID=11 )
IIRC it is believed that global destruction can happen with the impact of any asteroid bigger than 1 kilometer in diameter. Anything smaller can cause serious local damage or no damage at all (if it burns-up in the atmosphere).
To give an idea of the power of these things at various sizes how about this: The Tunguska asteroid in Siberia in 1908 was about 60 meters in diameter and exploded at an altitude of about 8 kilometers (about 26,000 feet). That one levelled 2,000 square kilometers of forest.
It’ll be a bad day for everyone if one of these things ever gets through.
Looks like 1 km is the transition between regional-to-global damage. IIRC, it was a 6 km object that wiped out the dinosaurs.
http://impact.arc.nasa.gov/torino/prof.html
This is a quick back-of-the-napkin calculation and math is not one of my strong points so if anyone can double-check this I’d appreciate it.
That said if we use your head instead of the earth as an aiming point (and adjust for your head’s size relative to the earth) then the asteroid AN10 would pass about 60 feet away from you (of course, the asteroid would now be smaller than a BB as well).
My Math (if anyone cares):
Assumptions:
Earth diameter is 11,404,800 feet
Asteroid at closest approach: 1,362,240,000 feet
Your Head: .5 feet (or 6 inches…a bit small maybe)
Earth diameter is to Head diameter as Asteriod distance is to X.
So…
11,404,800/.5 is equivalent to 1,362,240,000/x
Cross-multiply (.5 * 1,362,240,000) and divide (by 11,404,800) gives you 59.7222 – Call it 60 feet.
So you’re saying the asteroid going by the earth is like a bb going by my head about 60 ft. away.
What’s the big deal? I wouldn’t even notice a BB flying by 60 ft away. It’s not like it would give me a headache due to gravitational pull. Those scientists are wacky. There’s obviously nothing to worry about here.
I recently heard of a large ~ 1 kilometer asteroid that passed within the orbit of the moon in the 80’s(?). It came in from the sun side and wasn’t seen until after it had passed the earth. Not particularly amusing.
You’re right. And if you’re around in 2027 you won’t even notice a kilometer wide asteroid flitting by the earth 258,000 miles away either (except that I imagine it’ll rate a newsstory somewhere). The gravity from this also won’t give you a headache.
Of course, when you realize that the BB was shot at you from several thousand miles away you start to realize that that is actually remarkably close.
When you add the fact that such a thing hitting you would certainly kill you you might pay more attention. Relate it back up to the earth and realize that such an impact would mean the majority of life is wiped out on earth (if not all life) then it’s worth taking notice.
Even ‘little’ ones of a few tens of meters are devastating to the area they hit even if they aren’t global killers (Tunguska at ~60 meters in size is said to have been equivalent to a 10-20 megaton nuke…enought to flatten most of any major city). According to the website I linked earlier maybe 4-5 of this type (say 20-100 meters) strike per century.
So, while I wouldn’t hide under my bed because of this (as if that’d help) it IS worth being aware of. The chances may be remote but the stakes are so high and it clearly does happen that it is worth astronomers’ attentions.
Exactly. Space is vast. A few hundred thousand miles is considered close in comparison. Looking at maps of Near-Earth Asteroids’ orbits plotted with the Earth’s orbit, you may wonder why we aren’t hit more often.
The point is that it’s not a matter of IF Earth will be hit by a big asteroid, but WHEN. So, it’s important to keep track of these things in the hopes that we can do something to prevent it.
And like Jeff_42 said, when a big one hits, the results are going to be devastating.
IIRC, there is something like a 1-in-2,000 chance of the Earth being hit by a “large” asteroid/comet (I assume this means around 1 km or larger) in a person’s lifetime. Sounds high to me, but I haven’t tried crunching the numbers myself.
An to think that people ignore this but take out flight insurance when there is something like a 1-in-2,000,000 chance of a plane crash.
Link please? I’m not doubting you, I’m just really curious and would like to learn more.
Thanks.
I remember this too. No luck finding a link offhand. You may want to try these sites…
http://www.nearearthobjects.co.uk/
http://neo.jpl.nasa.gov/neo/pha.html
On this page, it appears that 1996 JA1 passed 1.2 LU from the earth on 19 May 1996. That’s the closest one this century.
Two in the 1980s were <2.0 LU away, though (1.8 and 1.5).
Quoth c_goat:
Someone’s wacky, all right, but it isn’t the scientists. Any scientist worth his salt will say something like “Based on the current data, our best estimate of the probability of an Earth impact from this object is approximately 1 in 500, but we’re still refining our measurements. We should have a better estimate within two or three days, so don’t worry about it until then”. If a reporter hears that, though, he’ll write down “Respected scientist says that asteroid might strike Earth, but doesn’t want to start a panic. Don’t everyone go rioting and looting the observatories, and maybe trying to stake out your neighbor’s house for a bomb shelter, d’ya hear?” on the front page. Then, in the two or three days that the scientist promised, when the data shows it’s a one in five billion chance, the papers will either put a footnote on the bottom of page six, or claim on the front page that it’s evidence of a coverup.
Re: the whole BB coming within 60 feet of your head analogy.
A BB flying by 60-feet away wouldn’t be very scary. But what if a 9mm bullet flew by 60 feet away? It might not exactly part your hair, but I bet you’d take cover if someone was firing bullets that close to you. These asteroids are very tiny compared to Earth, of course, but their effects on human civilization, and even the biosphere at large, would be very severe. Imagine getting hit by a BB moving at Mach 60…
Large must start at less than 1km, otherwise the earth would have been destroyed every 150,000 years on average (napkin math: 2K by a 75 year lifespan.) Maybe they meant a Tunguska-sized asteroid or larger.
Montfort: I don’t believe that I saw it online, it was a sidebar to an article describing the meteor seen from Denver(?)stadium during a football game. In any case it wasn’t the size or the near approach that got to me, it was the fact that it wasn’t detected until after it had passed.
Yeah, if I find the reference, I’ll post it.
But, FWIW, the Sept 2000 “Report of the Task Force on Potentiall Hazardous Near Earth Objects” has this to say on the frequency of impacts…
0.7 km…every 63,000 years (regional damage)
1.7 km…every 250,000 years (destroy large state plus global effects)
3 km…every 1,000,000 years (destroy large nation plus global effects)
7 km…every 10,000,000 years (destroy continent plus global effects)
16 km…every 100,000,000 years (global mass extinction)
It says the K/T impact (dinosaur) was a 10 km object (or 6 miles…correction to my previous post). Looks like we’re due for another one sometime between tomorrow and the next 75 million years. :eek: