Ping to topic and calculations down thread.
Posted on 02/29/2016 6:53:00 PM PST by rdl6989
Hey! “:^)
Ping to topic and calculations down thread.
Hit the hyperspace button.
NASA says Global Change has an Uncertain Orbit, every other lie is 110% accurate.
Where’s Roscoe Karns and his “We’re doomed” guys from the ZOT sequence?
Neglecting the effects of atmospheric drag, the density gradient in the atmosphere, and the competing gravitational pull of Earth and Moon (hint: have you ever noticed how many freaking *craters* the Moon has? I think it’s been ‘taking one for the team’ for aeons...)
You had to mention "hitting it" didn't you?
L-A-A-A-Z !! Over here!
The one that grazed Russia a few years ago was estimated at 20 meters, and exploded with about 30 times the energy of the Hiroshima bomb. So at 38 meters .....
I wouldn’t want it landing on my yard. Or my town for that matter.
“No chance”?
That’s not how probabilities work. The likely distance from Earth at the object’s closest approach can be plotted as a bell curve. The asteroid’s “best fit” orbit projects passage at 2.8 million miles away. It is said it “may” get as close as 19,000 miles, or, putting it another way, it may stray as close as 2.781 million miles away from the “best fit”, toward the Earth. If there is a 0.01% chance that the asteroid will come as close as 2.781 million miles from “best fit”, then the odds it will stray as close as 2.8 million miles from “best fit” are only slightly lower.
BTW, is the text you cite old data? A range of 21-52 meters diameter is fairly significant: We are looking at (assuming the thing does at least collide destructively with Earth’s atmosphere), on the low end, a Chelyabinsk type event, and on the high end, almost 18 times as much energy released as the Chelyabinsk event. (This assumes incoming velocity is the same — if this baby is coming in significantly faster, that increases the energy yield too. (The Chelyabinsk meteor, B4 it hit the atmosphere, is calculated to have been traveling at ~ 19 km/s, just over “average.)
Another way to look at it is that the Barringer crater meteorite is estimated to have been 50m diameter, with an impact speed of 12.8 km/s. Chelyabinsk is estimated at 500 kilotons, Barringer is estimated at 10 megatons, or a 20x bigger bang: not too far off my 18x calculation above.
The atmosphere slows down “little ones” more, assuming equal angles of entry, but, then, Chelyabinsk did not make it through the atmosphere, luckily for the locals! If it had come in near vertical at a city...
At any rate, should our new friend defy the odds and land on, say, me, the “bang” is going to be serious.
Interesting related article about a 2012 “Euro” fireball:
http://sattrackcam.blogspot.nl/2012/09/more-on-21-september-2012-fireball-why.html
These have nothing whatsoever to do with the probability of a given trajectory intersecting the globe of the earth.
...and the competing gravitational pull of Earth and Moon (hint: have you ever noticed how many freaking *craters* the Moon has? I think it’s been ‘taking one for the team’ for aeons...)
The mass of the earth is 81 times the mass of the moon, so the "intercepting power" of the moon is very little amplified over its "raw" angular coverage of ~.01^2/4pi = ~ 8e-6, or say 1/100,000, which is statistically insignificant.
Well, this ignores the concentration of orbits in the plane of the ecliptic. I'll give that a factor of ten, so I'll estimate 1/10,000 incoming objects to be intercepted by the moon, over the aeons.
Depends on the velocity of the asteroid, and the angle of incidence, right? As to whether it "skips" along the atmosphere or gets dragged in..
Unless you're saying, in principle that could happen, but in practice, all the asteroids which "would have" that happen, have already been eaten long ago.
The mass of the earth is 81 times the mass of the moon, so the "intercepting power" of the moon is very little amplified over its "raw" angular coverage of ~.01^2/4pi = ~ 8e-6, or say 1/100,000, which is statistically insignificant.
The moon orbits the earth, right? So if the asteroid comes in at such an angle that the moon is closer than the earth, ...just maybe it wins the gravitational tug of war.
Incidentally, has anyone tried a Monte Carlo simulation to figure out what sets of initial velocities (vector, not just speed) end up creating a lunar crater *facing* the earth? Or is it thought that some of those lunar craters were formed from (last model I remember hearing of, some 20 years ago or more) whatever collision it was which knocked a huge chunk out of the Earth to *become* the moon.
Right. The Moon does not have significant erosion, continental plates floating around / crashing into each other, etc. On Earth, most of the evidence has been erased.
Back in high school, I wrote a paper for my science course, based mostly on J. E. Enever’s 1966 article in Analog Magazine “Giant Meteor Impact”, which described the effects of a large impact in the sea, and the likely effects on the climate.
Enever speculated on even larger impacts, with the impact of a Juno-esque body being “the recipe for instant Pasteurized planet”. I have been fascinated ever since, and of course Shomaker-Levy hitting Jupiter was amazing too...
https://www.youtube.com/watch?v=CiLNxZbpP20
YouTube vid of Shomaker-Levy, actual impacts starting around 1:00. Each of these would have devastated an area up to thousands of miles across, on Earth. Fragment “G”, probably the largest, generated an estimated 6 MILLION megatonnes of TNT.
That’s quite a list...
I don’t think I have time to view that many orbits! But, thanks!
Well yes, but the Canyon Diablo was nickle/iron. It would ablate differently and have greater kinetic energy than the Chelyabinsk type event. When the Barringer meteorite was finally found, as I remember,on the south rim of the crater, it had a diameter of nineteen feet.
BTW, a small piece of Chelyabinsk did make it into a frozen lake.
There is a basic formula, that I don't remember right now, but it states that a body has a chance of making it to earth if it enters the atmosphere with a weight of over eight tons.
Anyhow, enjoy the NASA web site.
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