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Discussion Starter · #1 ·
http://www.popularmechanics.com/spa...roid-will-pass-an-astronomical-hairs-breadth/

Terribly written article, much worse that is the usual for PM. Example: the trajectory is uncertain, the flyby can happen at 1.5 million miles or 11.000 miles.
If they can be sure of 1 million miles how can be sure or 11,000 distance (versus 0 miles, for example). Another one: the object is 100 feet in diameter versus 60 feet for Chelyabinsk meteor. So, according to the article, the explosion would be twice as big. According to a simple math it would be 5 times as great.
 

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http://www.jpl.nasa.gov/news/news.php?feature=4888

A better source I think is NASA.

During the upcoming March 5 flyby, asteroid 2013 TX68 could fly past Earth as far out as 9 million miles (14 million kilometers) or as close as 11,000 miles (17,000 kilometers). The variation in possible closest approach distances is due to the wide range of possible trajectories for this object, since it was tracked for only a short time after discovery.

Scientists at NASA's Center for NEO Studies (CNEOS) at the Jet Propulsion Laboratory in Pasadena, California, have determined there is no possibility that this object could impact Earth during the flyby next month. But they have identified an extremely remote chance that this small asteroid could impact on Sep. 28, 2017, with odds of no more than 1-in-250-million. Flybys in 2046 and 2097 have an even lower probability of impact.

"The possibilities of collision on any of the three future flyby dates are far too small to be of any real concern," said Paul Chodas, manager of CNEOS. "I fully expect any future observations to reduce the probability even more."
But certainly worth noting. :)
 

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It does make you wonder with all of that debris out there that can appear suddenly from the dark that the planet has not had more significant hits.

Jupiter is on the job for the most part and then there's dumb luck big sky I guess.
 

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Our planet has had many significant hits throughout geologic time. Earth has had proportionally as many impacts as the Moon or Mars. The reason we do not see as many craters here as we see on Mars and the Moon is that the Earth has a dynamic surface and crust. Moon and Mars do not.

The earth's surface has been continually modified not only by erosion but also by plate tectonics, where crustal plates dive under other crustal plates and are obliterated and recycled. So many impact features have been lost on earth. Plate tectonics are not occurring on the Moon or on Mars.

Many existing craters on earth have had their rims and other identifying features either eroded away or buried. Some impact features may be detected with geophysical methods.

I have actually seen several impact craters using 3D seismic data. The ones I have seen on seismic are buried quite deep. I can't say where they are, but these are not in the USA.

A good example of an eroded crater with a preserved central rebound structure is Sierra Madera, south of Fort Stockton, Texas.

If you look around, they are out there. Google astroblemes, meteor craters, impact features, etc.

The one that made the tiny crater near Odessa allegedly released enough energy to kill everything within a 20-mile radius.

It wouldn't take a very big space rock to really make a mess of a city.
 

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http://www.popularmechanics.com/spa...roid-will-pass-an-astronomical-hairs-breadth/

Terribly written article, much worse that is the usual for PM. Example: the trajectory is uncertain, the flyby can happen at 1.5 million miles or 11.000 miles.
If they can be sure of 1 million miles how can be sure or 11,000 distance (versus 0 miles, for example). Another one: the object is 100 feet in diameter versus 60 feet for Chelyabinsk meteor. So, according to the article, the explosion would be twice as big. According to a simple math it would be 5 times as great.
The variance you're talking about in distance is showing EXTREMES. It'll almost certainly happen somewhere in the middle of that (basically it'll miss).

As for the damage difference there's more to how much damage is caused than just size ... composition has every bit as important as a role. So while this asteroid might be five times larger it also is significantly more ice.
 

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Discussion Starter · #10 ·
The variance you're talking about in distance is showing EXTREMES. It'll almost certainly happen somewhere in the middle of that (basically it'll miss).

As for the damage difference there's more to how much damage is caused than just size ... composition has every bit as important as a role. So while this asteroid might be five times larger it also is significantly more ice.
This is very very simple, no point in making it complicated:
1. If one shows an uncertainty spread, both sides must be to the same decimal points. Elementary honesty. So if the best they can determine is within 500,000 miles (1 1/2 million miles in the report), then the other side can't be within 1000 miles accuracy (11,000 miles in the report). So it is dishonest. Now we all know they always lie (and want to avoid panic), so I would have chuckled and let it go. But...
2. If Russian "meteor" was 60 feet in diameter, and the new one 100 feet, then the explosion would be 5 times greater, not 2 times greater. This particular lie is outrageous (and unnecessary). And the composition has nothing to do with this, since they can't possibly know it. The power would also depend on angle, but the can't possibly know that either.

And if I would rely on past experience with NASA (they underestimated explosive power of Russian meteor by 500 times, this new asteroid would be 3 miles in diameter instead of 100 feet.
 

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The variance you're talking about in distance is showing EXTREMES. It'll almost certainly happen somewhere in the middle of that (basically it'll miss).

As for the damage difference there's more to how much damage is caused than just size ... composition has every bit as important as a role. So while this asteroid might be five times larger it also is significantly more ice.
Angle of entry is extremely important as well. Given a very shallow entry it's likely to burn up before getting low enough to damage anything (or at least significantly shrinking in size before it impacts/explodes), or even just ricocheting back out.
 

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Discussion Starter · #12 ·
Angle of entry is extremely important as well. Given a very shallow entry it's likely to burn up before getting low enough to damage anything (or at least significantly shrinking in size before it impacts/explodes), or even just ricocheting back out.
Much more complicated then this (even though the angle MIGHT be important):
last year there were a "bolide" on south to north trajectory, which was flying at ZERO angle (horizontally). It flew for 3000 miles, never striking the Earth and just disappeared north of Canada (no witnesses there).
 
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