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Old 08-04-2019, 10:01 AM
 
Location: USA
1,601 posts, read 626,526 times
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https://www.nj.com/news/2019/08/6-as...-building.html

I have reserved my spot on an Uber Space Rocket for August 9th
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Old 08-04-2019, 10:35 AM
 
1,211 posts, read 431,489 times
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"heading in the direction of our planet"

is not the same as

"will be tracking about 5 million miles away from our planet"
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Old 08-04-2019, 10:57 AM
 
7,997 posts, read 1,853,702 times
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From the linked article in the OP (quote, my italics): Just last week, a small asteroid that was not being closely tracked flew as close as 45,000 miles away from our planet, leaving some astronomers stunned, the Washington Post reported.

“It snuck up on us pretty quickly,” one astronomy expert told the Post. “It’s probably the largest asteroid to pass this close to Earth in quite a number of years.”
[end quote]

This is much more alarming, and although the article didn't say how large it was, but I guess it could have made a dent and upset quite a few people's plans if it had hit Washington, D.C. or some other large metro area!
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Old 08-04-2019, 05:23 PM
 
Location: Seattle
2,257 posts, read 483,431 times
Reputation: 2126
Close one. It looks like 2019 OK was somewhat larger than the object that created Meteor Crater in Arizona, although it was stony rather than metallic. Big enough to make a dent, at any rate, assuming it's solid and not a rubble pile.

https://en.wikipedia.org/wiki/2019_OK
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Old 08-05-2019, 10:46 PM
 
Location: PRC
3,231 posts, read 3,360,329 times
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I really dont know what good it will do to tell us when we (some of us sheep) are about to die.

...And that is probably an opinion shared by many, particularly since we may not know who will be in the firing line due to last minute breakups etc. Other countries may decide not to tell their citizens at all and to just deal with the aftermath.
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Old 08-06-2019, 09:20 AM
 
22,774 posts, read 17,250,171 times
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Quote:
Originally Posted by ocpaul20 View Post
I really dont know what good it will do to tell us when we (some of us sheep) are about to die.

...And that is probably an opinion shared by many, particularly since we may not know who will be in the firing line due to last minute breakups etc. Other countries may decide not to tell their citizens at all and to just deal with the aftermath.
If an asteroid big enough to destroy a city were to be headed our way, I think in most instances we would know far enough ahead of time where it was going to strike. A warning could then be given so that people could evacuate to a safe location. At least it would give people a chance.
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Old 08-06-2019, 01:39 PM
 
5,203 posts, read 8,204,697 times
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Quote:
Originally Posted by Mike555 View Post
If an asteroid big enough to destroy a city were to be headed our way, I think in most instances we would know far enough ahead of time where it was going to strike. A warning could then be given so that people could evacuate to a safe location. At least it would give people a chance.
That would be fine in instances where an object is spotted long before an impact. Such sightings would primarily be from asteroids approaching from farther out in the solar system. However, some have approached from the direction of the Sun were hidden by solar glare making detection very difficult. In some instances, detection had only been a few hours before a flyby. Some were not detected at all until after the fact.

The asteroid that flew over Chelyabinsk Russia was detected after the explosion in the atmosphere and the trail of the object could be seen. That object was thought to have been about 66-feet in size, about the size of a 6 story building. The mass of the object is thought to have been heavier than the Eiffel Tower. It's blast was estimated to be about 400 to 500 kilotons of TNT (26-33 times the energy of the atomic bomb at Hiroshima). The blast occurred about 18.5 miles above. The trail and flash were caught by cameras, but too late to do anything about it and no time to give any warning to evacuate or head for shelter. On the plus side of potential impacts, most of the Earth's surface is covered by water and land surfaces that are either wilderness or scarcely populated. Although an impact to a populated city is not impossible, odds of such an object hitting a city are much lower. Still, it makes me wonder how much damage it would've caused if it had exploded over a large city like Tokyo or New York City.
https://en.wikipedia.org/wiki/Chelyabinsk_meteor

There have been recent flybys that were spotted within hours of approach. These objects were harmlessly a long way from the Earth, although some passing within the orbits of the Earth and Moon. It's hard to spot such objects well in advance. We can spot some, but not all of them.

I think it's also fair to say that objects that are spotted coming from beyond the orbit of the Earth are difficult to predict a precise path, although much larger objects have been identified and can be reasonably predicted. Even at that, it takes very careful observation and understanding its trajectory which takes time in terms of months or years. Still, there's a lot of stuff in the solar system. The vast majority of smaller ones haven't been identified, objects that could still be potentially damaging to cities. There could be hundreds of millions, maybe more, of them. We've identified most of the largest ones, but not all of them. The majority of any asteroid seem to be in fairly stable orbits, such as the Asteroid Belt. But all it would take is a nudging collision between some of them to send others out in any direction, including crossing the orbit of the Earth.
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Old 08-06-2019, 03:36 PM
 
Location: Here
1,471 posts, read 358,645 times
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Quote:
Yes, an asteroid that’s almost 1,900 feet in diameter and zipping at a speed of 10,000 mph is capable of causing massive destruction if it were to make a direct hit on any city on Earth. However, it will be tracking about 5 million miles away from our planet when it flies past us on Aug. 10, according to a report by CNN.
That's a fairly large asteroid. But five million miles is not close. A circle with a radius of five million miles covers an area exceeding 78 trillion miles. A cross-section of the Earth is less than 1/1,500,000th as much as that. If we compared it that to a human being with a width of about 18 inches, it's roughly the equivalent of getting 'missed' by a bullet that never comes close than about 1000 feet away from you.

Quote:
Just last week, a small asteroid that was not being closely tracked flew as close as 45,000 miles away from our planet, leaving some astronomers stunned, the Washington Post reported.
Now that one was closer. But still, less than 1 in 100 objects that comes within the sphere encompassed by 45,000 miles on all sides of Earth will encounter the atmosphere. And if it had, the question of what would have happened is open. The median estimate of its size suggests an explosion of about 10 megatons. Would it reach the surface? That depends on its composition, which is unknown. Damage? That depends on where it impacts. Most impact locations would result in only a minor human impact. Of course, it could hit a city - but most people don't seem to understand just what a small percentage of the Earth is densely populated urban areas.

Quote:
Originally Posted by Mike555 View Post
If an asteroid big enough to destroy a city were to be headed our way, I think in most instances we would know far enough ahead of time where it was going to strike. A warning could then be given so that people could evacuate to a safe location. At least it would give people a chance.
This is incorrect.

A zone of impact could be predicted, but it would be a very large area (as in, a hemisphere), only gradually becoming more precise as the object approached Earth. Even specificity as general as, say, England or Iowa would not be possible until it was within a hour or so of impact.

Evacuate England/Iowa in the next 90 minutes: read, set, go! Good luck with that...
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Old 08-06-2019, 03:39 PM
 
22,774 posts, read 17,250,171 times
Reputation: 9481
Quote:
Originally Posted by NightBazaar View Post
That would be fine in instances where an object is spotted long before an impact. Such sightings would primarily be from asteroids approaching from farther out in the solar system. However, some have approached from the direction of the Sun were hidden by solar glare making detection very difficult. In some instances, detection had only been a few hours before a flyby. Some were not detected at all until after the fact.

The asteroid that flew over Chelyabinsk Russia was detected after the explosion in the atmosphere and the trail of the object could be seen. That object was thought to have been about 66-feet in size, about the size of a 6 story building. The mass of the object is thought to have been heavier than the Eiffel Tower. It's blast was estimated to be about 400 to 500 kilotons of TNT (26-33 times the energy of the atomic bomb at Hiroshima). The blast occurred about 18.5 miles above. The trail and flash were caught by cameras, but too late to do anything about it and no time to give any warning to evacuate or head for shelter. On the plus side of potential impacts, most of the Earth's surface is covered by water and land surfaces that are either wilderness or scarcely populated. Although an impact to a populated city is not impossible, odds of such an object hitting a city are much lower. Still, it makes me wonder how much damage it would've caused if it had exploded over a large city like Tokyo or New York City.
https://en.wikipedia.org/wiki/Chelyabinsk_meteor

There have been recent flybys that were spotted within hours of approach. These objects were harmlessly a long way from the Earth, although some passing within the orbits of the Earth and Moon. It's hard to spot such objects well in advance. We can spot some, but not all of them.

I think it's also fair to say that objects that are spotted coming from beyond the orbit of the Earth are difficult to predict a precise path, although much larger objects have been identified and can be reasonably predicted. Even at that, it takes very careful observation and understanding its trajectory which takes time in terms of months or years. Still, there's a lot of stuff in the solar system. The vast majority of smaller ones haven't been identified, objects that could still be potentially damaging to cities. There could be hundreds of millions, maybe more, of them. We've identified most of the largest ones, but not all of them. The majority of any asteroid seem to be in fairly stable orbits, such as the Asteroid Belt. But all it would take is a nudging collision between some of them to send others out in any direction, including crossing the orbit of the Earth.
That's all certainly true. New Near Earth Objects larger than 460 feet are being discovered at a rate of 500 or so a year so there always exists the possibility of a so far undiscovered NEO sneaking up on earth undetected. As more and more of the NEO's are catalogued we can keep an eye on them and provide the necessary warning if one should be on target to hit earth. It's fortunate that a Chelyabinsk Russia event is a rare occurrence, and the 1908 Tunguska event an even rarer occurrence.
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