Asteroid explosion over Indonesia

From NASA’s Spaceweather.com

INDONESIAN ASTEROID: Picture this: A 10-meter wide asteroid hits Earth and explodes in the atmosphere with the energy of a small atomic bomb. Frightened by thunderous sounds and shaking walls, people rush out of their homes, thinking that an earthquake is in progress. All they see is a twisting trail of debris in the mid-day sky:

This really happened on Oct. 8th around 11 am local time in the coastal town of Bone, Indonesia. The Earth-shaking blast received remarkably little coverage in Western press, but meteor scientists have given it their full attention. “The explosion triggered infrasound sensors of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) more than 10,000 km away,” report researchers Elizabeth Silber and Peter Brown of the Univ. of Western Ontario in an Oct. 19th press release. Their analysis of the infrasound data revealed an explosion at coordinates 4.5S, 120E (close to Bone) with a yield of about 50 kton of TNT. That’s two to three times more powerful than World War II-era atomic bombs.

The asteroid that caused the blast was not known before it hit and took astronomers completely by surprise. According to statistical studies of the near-Earth asteroid population, such objects are expected to collide with Earth on average every 2 to 12 years. “Follow-on observations from other instruments or ground recovery efforts would be very valuable in further refining this unique event,” say Silber and Brown.

###

I worry about asteroid events more than I do climate change. Here’s why, Spaceweather.com has this summary:

near_earth_asteroids

A bunch of that “stimulus” money would be better spent for humanity if we worked on building an asteroid detection and defense system.

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75 thoughts on “Asteroid explosion over Indonesia

  1. This asteroid event is indeed frightening. Thanks for pointing out something that warrants legitimate concern.

  2. A real threat warrants a real response.
    It’s a good thing that this rock broke up/exploded harmlessly in the atmosphere. Imagine if it had hit a major city.
    The key difference between asteroid strike threat vs AGW threat? There is actual physical evidence for the former.

  3. A bunch of that “stimulus” money would be better spent for humanity if we worked on building an asteroid detection and defense system.
    You’ve got that right… but asteroids will just kill us. You can’t regulate asteroids. CO2, on the other hand… Regulate it, and you regulate everything.

  4. It’s disgusting how much is spent on Asteroid detection compared to the astrology of climate change!
    We need mega $$ spent on asteroids ASAP, otherwise one of these could wipe out an entire city instantly!

  5. Hmmmmm I wonder what one of those say 300m or larger in a direct collision would do for global warming for the survivors? Perhaps we are studying the wrong possible possible catastrophic event
    Bill Derryberry

  6. “An asteroid came at us
    but what could we do?
    We’d spent all our money
    to reduce CO2.

    And now we’re just green ooze
    with bubbling gas.
    Lord Al G. would be proud of US;
    “Green at last!”
    But though we’re green
    we’re also blue;
    we miss that lovely
    CO2.”
    excerpt from the Tale of Goregamash

  7. In the mid-1930’s I was living in North Plainfield, NJ. In the middle of the night a small meteorite passed over and hit the ground. The remains were the size of a baseball, according to the newspaper, but the passage caused a thunderous roar loud enough to awake everyone. I can imagine that a meteor the size of the Indonesion one would be cause for great fright.

  8. The director of NASA’s Planetary Science Division, James Green, said, ”Finding them is one thing, but you have to know your enemy.” So far, NASA has spent $US41million ($A59.65million) on asteroid detection and deflection, but the Near Earth Object Program is running out of money!!!!!!!!
    ”It’s just barely hanging on,” Mr Shapiro said.
    The amount of money spent on global warming research since 1990 is now about $US50 billion
    To adhere to the Kyoto Protocol and thereby postpone warming by just five years to 2100, the cost would be $US180 billion annually.
    Preventing HIV/AIDS turns out to be the very best investment humanity can make … For $US27 billion, we can save 28 million lives over the coming years.
    Investing $US12 billion would probably halve the number of people dying from malnutrition, currently almost 2.4 million a year; $US13 billion would reduce deaths from malaria, now a million a year, by the same proportion. UNICEF estimates that just $US70-80 billion a year could give all Third World inhabitants access to the basics such as health, education, water and sanitation.
    It would be funny spending billions on global warming only to have a big asteroid just wipe us out!
    REPLY: And who’d be laughing about that? Cockroaches maybe once they become sentient and figure it out. – A

  9. Another close call, and our Congress hasn’t passed a law about it.
    It isn’t the case, but the smoke trail of the meteor looks like it took a u-turn.
    That’s caused by the varying wind speeds at different altitudes.

  10. NASA contends that it has been assigned the mission of monitoring for NEA’s, but Congress has failed to fund.

  11. Did you not know that in 1812 the Paris Institut, in terms of natural Philosophy second only in prestige to the Royal Society, solemnly declared the idea that stones fell from the sky was an absurd old wives tale.
    A few months later there was a fall of meteorites just outside Paris.
    Kindest Regards

  12. This asteroid was clearly caused by AGW. There will be many more asteroids in the future unless we act to reduce carbon emissions now.

  13. The second angel sounded, and something like a great mountain burning with fire was thrown into the sea; and a third of the sea became blood, … Revelation 8:8

  14. Maybe Gaia just called in some favors from the asteroid belt to hose us vermin off her. I guess things are tight all over.

  15. But CMEs would wipe out our satellites (1859!) and you wouldn’t be able to post.
    Well, sweet dreams!

  16. What about asteroids heading our way from behind the sun? I bet our telescopes aren’t able to see these. Side note: Ive visited this site many many times, and I only just now noticed a tiny happy face in the bottom left of this web page. I need a bigger telescope!

  17. I had the opportunity as a young boy to observe a large object pass over the Lake Tahoe area. It seemed to be about the size of a house, but, unlike those I often see in news reports, it was not burning, smoking, roaring or whistling. It passed across the entire horizon silently, in just a few seconds, at what appeared to be less than 5,000ft of altitude. I thought I could see a metallic sheen on some surfaces, suggesting a meteor. But, No shock wave, no sound, and higher than it appeared, as it cleared a nearby mountain top. Leaving me wondering if I had witnessed the passing of an object traveling outside the atmosphere, and therefore much larger than it appeared.

  18. An asteroid explodes with the force of two or three Hiroshima bombs and what are the politicians and protesters shouting about? A pitiful 380 ppm Carbon Dioxide.
    What annoys me is only hearing about the detonation 19 days later. Could have been worse I suppose, it could have explodeded locally.

  19. Wow. This wasn’t in the news? I mean, I know that if it bleeds it leads, but damn. THREE atomic bombs worth of force is newsworthy in any event.

  20. I saw one 10 years ago, bright red, loud, over head it turned to dark red then black.
    don’t know if it hit the water at lake Michigan or reentered space!
    it was an eye opening experience. sleep well.

  21. Wish there was some tracking on this…
    I have been attracted to Comet 2P/Encke and the Taurid complex on several occasions.
    “Some consider the Bronze Age breakup of an originally larger comet of which Comet Encke is a member to be responsible for ancient destruction in the Fertile Crescent, perhaps evidenced by a large (unconfirmed) meteorite crater in Iraq identified as Umm al Biinni lake.[2] The origin of the swastika has also been connected with Comet Encke. It has also been suggested that the object likely to have been responsible for the Tunguska event in 1908 was a fragment of Comet Encke.”
    http://en.wikipedia.org/wiki/Comet_Encke
    “The Taurids are an annual meteor shower associated with the comet Encke.”
    “Encke and the Taurids are believed to be remnants of a much larger comet, which has disintegrated over the past 20,000 to 30,000 years,”
    “In total, this stream of matter is the largest in the inner solar system. Due to the stream’s size, the Earth takes several weeks to pass through it, causing an extended period of meteor activity, compared with the much smaller periods of activity in other showers. ”
    “The Taurid stream has a cycle of activity that peaks roughly every 2500 to 3000 years, when its core passes nearer to Earth and produces more intense showers. In fact, because of the separate “branches” (night-time in one part of the year and daytime in another; and Northern/Southern in each case) there are two (possibly overlapping) peaks separated by a few centuries, every 3000 years. Some astronomers note that dates for megalith structures such as Stonehenge are associated with these peaks.”
    http://en.wikipedia.org/wiki/Southern_Taurids
    “The Taurid Complex, related to Comet 2P/Encke, is a massive stream of material in the inner solar system”
    “while the orbits of some particles are quite dispersed, it is still likely that the Taurid stream has a narrow and dense core consisting of particles concentrated near the orbit of the stream’s parent object, which is presumably related to Comet 2P/Encke. As the orbits of the material constituting this narrow, dense core have been subject to perturbations over thousands of years, it may be inferred that intense bombardment episodes have resulted at epochs when the material reaches Earth intersection”
    (the broader darker line of orbit designates above or below the ecliptic plane, opposite for the thinner line)
    [attachment=1]north taurids.png[/attachment]
    [attachment=0]south taurids.png[/attachment]
    “action of a mean motion resonance with Jupiter can produce structure in a meteoroid stream, concentrating meteoroids in a dense swarm. More specifically, predictions tabulated by Asher & Clube of enhanced meteor and fireball activity from a Taurid Complex swarm in the 7:2 resonance are compared with observational data collected in Japan over several decades. This allows increased confidence in the Taurid swarm theory, and more generally could mean that resonant trapping is a dynamical mechanism affecting a significant amount of meteoroidal material in the inner Solar system. ”
    http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1998MNRAS.297…23A&db_key=AST&page_ind=0&data_type=GIF&type=SCREEN_VIEW&classic=YES
    “We show that a statistically significant number of Earth-crossing asteroids are part of the Taurid Complex of interplanetary objects”
    http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1993MNRAS.264…93A&db_key=AST&page_ind=0&data_type=GIF&type=SCREEN_VIEW&classic=YES
    “It is shown that the giant comet breakup hypothesis has a clear basis in astronomical fact”
    http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1987MNRAS.225P..55C&db_key=AST&page_ind=0&data_type=GIF&type=SCREEN_VIEW&classic=YES
    “Recent astronomical data are employed to make a detailed analysis of periodic terrestrial bombardment by molecular cloud debris during revolution around the Galaxy. Passage through the Gould Belt 3-6 Myr ago would have resulted in glaciation, geomagnetic reversals, and extinction events, all of which have left evidence. The break up of large comets in the solar system after passage through the Belt would produce a large dust and meteor input to the atmosphere, causing a rise of up to 1 percent of C-14 in the atmosphere. The level would be sufficiently high to affect a full climatic cycle. Some glaciation could also occur, and the last Ice Age could have been caused by the progenitor of comet Encke, part of which was the Tunguska meteorite, an interstellar object. It is estimated that further debris from the zodiacal cloud will intersect earth during the period 2000-2400 AD.”
    http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1984MNRAS.211..953C&db_key=AST&page_ind=0&data_type=GIF&type=SCREEN_VIEW&classic=YES
    From this information we can deduce the following:
    a. there is a system of asteroids/cometary debris that intersects earths’ orbit periodically
    b. the streams intersect each other at the point of earth orbit intersection
    c. the streams have large, dense objects, concentrated in a stream core
    d. the earth intersects these ‘cores’ about every 3000 years, and we are due about now
    e. it may take two weeks for the earth to pass through the stream core
    therefore, we can surmise that a catastrophic, extinction level event ‘could’ occur every 3000 years approximately….
    this event would be a constant bombardment by many asteroids and cometary impacts at 65,000 MPH (not including earths velocity) lasting about two weeks in duration, giving all corners of the globe the destruction required to eliminate civilizations on a macro scale…..
    this is a justifiable hypothesis, so far….

  22. A definition of governmental insanity:
    Propose to incur costs of 100s of BILLIONS of $ to combat the computer-generated ”threat” of AGW, while the earth has been stable or cooling since 1998. BUT:
    Refuse to spend a few paltry 10s of Millions of $ to properly catalog and plot all detectable NEOs.
    One of these days a 100+ meter NEO will come wandering into the atmosphere at a speed of 10-12 miles per SECOND or so. . . . Or maybe something the size of Apophis (~350 meters) that hasn’t been detected yet. . . . . and Planet Earth will have a REALLY bad day.
    FOOTNOTE: Yeah; I know: Apophis is NOT going to smack us in 2029; and the odds it will thread the keyhole and then hit us in 2036 are now down to about 1 out of 250K. There are other rocks out there; count on it.

  23. In 1908 a meteorite exploded above Tunguska, it was larger than this one in Indonesia, about a 100 meters and it exploded with an estimated yield of 10-15 megatons, that is the size of large nuclear weapon. A forrested area of about 2100 square km was leveled and the explosion measured 5 on the Richter scale. That is good enough to destroy a large city if it was in the right place.
    The list of incidents since that june day in 1908 is long. With the explosion over Indonesia being the largest since 1908. And they could be mistaken for nuclear explosion, its what happend in 1979 when a Vela satellite detected a small nuclear explosion, or so they thought since no radioactive fallout was found.
    With several countries around the world trying to obtain nuclear weapons or already having them the chance that we would make that same mistake again is rather high and therefore the risk of smaller or larger nuclear exchange of weapons is also a possible thing that could happen in the near future.
    Nuclear weapons and meteorites are real, they are not some output of a model.

  24. To add… the entire premise is that the Taurid Complex was once a large body…and the assumption of it’s demise ‘about’ 20,000 years ago…..leaving a tremendous amount of large and small debris….which is now concentrated in a narrow, dense, core….
    the earlier ‘passes’ were readily noticeable and destruction was periodic….therefore, the ‘planet/comet’ WAS there, which would account for the ancient ‘myths/tales’…..
    there are several different avenues of thought and research on the ‘comet stream’….different timelines of intersection, things like that….one researcher says every 2000 years, another says we intersect every 3000 years, etc….
    “Therefore, although the Taurid stream is very broad, at the core of the stream we expect a concentration of meteoroids and cometary fragments, including objects of Tunguska size. As a result of Jupiter’s gravity, the orbit of this central concentration changes over thousands of years, sometimes being brought into intersection with the Earth’s orbit (Figure 1). That is, in 3 dimensions, the central concentration usually misses the Earth’s orbit, but there will be times when it intersects the Earth’s orbit. At these times, the impact frequency on the Earth is much higher. Assuming the parent object is closely related to Comet Encke, it seems that the last intersections were around AD 300 to 500, and before that somewhat earlier than 2000 BC (Figure 1), although there is some uncertainty in these calculations. The most recent intersections may have been a couple of centuries earlier, and the intersections before that could have been as early as 3000 BC. Despite the uncertainty, the calculations always show that there are `dangerous times’ lasting a couple of centuries, when there is a greatly increased impact frequency, followed by a few thousand years when the Earth’s orbit is not intersected by the Taurid core. The next intersection in the future will be around AD 3000”
    http://www.perigeezero.org/treatise/timeline/index.html
    the above site suggests the rise in sea level and ice ages were caused by intersections with the meteor/asteroid stream, as well as the destruction of civilizations….due to the ice composition of the huge comet that broke up and rained on earth…
    I’ve seen ‘expected’ intersection dates of 2000 AD to 3000AD….so, they don’t really know exactly where the dense core stream is, and are not sure if it drifts up and down or not, which would change intersection dates greatly….
    “Theoretical radiants for macroscopic Taurid objects are then presented and compared with observations of the nighttime and daytime Taurid meteor showers. These are found to be broadly similar in form, given the sparsity of some of the data, adding weight to the hypothesis that this sub-jovian complex contains kilometre-plus asteroids. ”
    http://adsabs.harvard.edu/abs/1995EM&P…68..155A
    the debris is large enough, in sufficient quantity, appears periodic in nature, is relative to the ancient myths/tales/prophecies, and fits some of the timelines for previous abrupt climate change and near extinction events….
    plus, the astrophysicists and astronomers aren’t sure when we would intersect, as they are only now figuring out that it does exist, and why it does….

  25. a jones (18:18:38) :
    “Did you not know that in 1812 the Paris Institut, in terms of natural Philosophy second only in prestige to the Royal Society, solemnly declared the idea that stones fell from the sky was an absurd old wives tale.
    A few months later there was a fall of meteorites just outside Paris. ”
    That occurred about 10 years earlier. The meteorite fall was the famous event of April 26, 1803 (not 1813), at l’Aigle, in northern France.

  26. Copenhagen is a really beautiful city and I would be devastated if anything happened to it – and of course the fine and friendly Danish people who live there.
    But sometimes even the blackest cloud has a silver lining. Now, if one of these asteroids was to …… [snip]

  27. Did I read that Correctly? 10 METERS WIDE?! Good god, if that did impact, that would of heavily damaged a small city. Ok, perhaps this should be a wake up call to the government to stop worrying about climate change and start worrying about NEO’s.

  28. Robert van der Veeke (22:29:47) :
    In 1908 a meteorite exploded above Tunguska, it was larger than this one in Indonesia

    The jury is still out on Tunguska. No incriminating evidence has yet been found to pinpoint the exact cause as yet.
    However you may or maybe not correct in suggesting that this latest event in Sulawesi is the largest since Tunguska. The reality is that other events in the last 100 years may have happened and never had widespread coverage. It’s taken a couple of weeks to get worldwide media exposure to this event. The only reason it’s in the worldwide media now is because on modern mass communications and the internet. Sulawesi had very poor communications only 20 years ago.

    Tanner Waterbury (00:58:47) :
    Did I read that Correctly? 10 METERS WIDE?! Good god, if that did impact, that would of heavily damaged a small city.

    More like a large city.

  29. Robert van der Veeke (22:29:47) :
    “The list of incidents since that june day in 1908 is long. With the explosion over Indonesia being the largest since 1908. And they could be mistaken for nuclear explosion, its what happend in 1979 when a Vela satellite detected a small nuclear explosion, or so they thought since no radioactive fallout was found.”
    I seem to recall something similar at around the same time. Weren’t the colonials up in arms about suspected high altitude thermo-nuclear explosions being detected by their satellites, they checked with us good old Brits but our defence chaps had heard nothing. I believe it did make the news at the time, but of course that was when the BBC was a reliable, impartial, professional news gathering & reporting organisation, beholden to no one. A few commentators at the time suggested the Americans needed to check their equipment, under the friendly rivalry of who has the best kit. However there was a good quality BBC Horizon (science & I have said this before ;-)) prog on it around 12+ years ago, which noted this occurrence where US satellites detected what appeared to be sizable upper atmospheric explosions which quite naturally suggested that they may be under attack, but which also high-lighted the regular nature of these NEO hitting the atmosphere. It also high-lighted the checks & balances in place for western powers as opposed to anti-nuclear campaigners always complaining that the US could & would launch a first strike out of hand. Now of course we have today’s politically correct version of armageddon group hug theory, so that WAGTD, poor, as a result of man’s folly! Nothing personal but one can take this group hugging theory a bit too far. At least I hear our “Beautiful Leader” is meeting his European counter parts to discuss this further. (I am also alarmed to hear that “European Union” warships are out on patrol somewhere, last I heard we still had the Royal Navy, oh well ho hum.)

  30. The AGW liberal elites would welcome an asteroid strike because it would instantly reduce the worlds population that is the real threat to the earth. At least that’s what they think.
    I check the spaceweather.com web page a lot and it is scary to see the Lunar Distances recent space debris has missed the earth by. I wonder about the ones that aren’t seen until the last minute? Maybe a “thicker” atmosphere is better to help shield us from this stuff.

  31. Does anyone know what the warmist’s/green’s views are on possible asteroid impacts? Do they even have a view?

  32. RE Tanner Waterbury (00:58:4
    A 10m body explodes in the atmosphere due to stress and therma effects, so it’s not something to worry about.
    Here’s a website that shows 50 impact structures globally.
    http://geology.com/meteor-impact-craters.shtml
    One of the most recent impact events occured at Wabar in the Empty Quarter of what is now Saudi Arabia, some 2-400 years ago.
    The biggest surviving piece found to date, weighs 2.4 tons.
    A fall was reported in 2002 near Vitim in Siberia, possibly a cometary fragment some 50-100m in diameter that also airburst.

  33. I guess that was a real Bone shaker.
    Improving our observing capabilities sounds like a much better use of public money than sending 20,000 people to Copenhagen for some xmas shopping. Presumably this was missed on the way in because current observing systems focus on known or assumed high risk areas of space?

  34. Very impressive!
    Such near earth objects may be dangerous, but more often just incredibly fascinating to observe. There are many more such objects than most people are aware of.
    On December 7 and 8, 2004, a small PHA (PHA=Potentially HAzardous) object called 2004 RZ164 passed close to the Earth (< 0.2 AU), and I was able to make a couple of videos of it, from series of telescopic long exposure webcam images. That was a thrill!
    My image and videos of 2004 RZ164 as seen through an 8 inch amateur telescope.
    http://arnholm.org/astro/deepsky/a2004_rz164/
    Here is the 2004 RZ164 orbit in 3D in the JPL small body browser
    http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2004%20RZ164;orb=1

  35. I experienced something similar 30 years ago when I was living in Sweden.
    It was in late May and I was watching the TV news.
    Suddenly there was a bright flash. Despite a clear blue sky I then automatically assumed that a front was coming with thunder and rain from the south.
    A while later, for how long I don’t know, I heard a huge bang. It felt as if a military artillery gun was firing right outside my window or as if someone had thrown a hand grenade next to the house.
    At first I didn’t connect the dots.
    It was only a few minutes later, when someone else asked me to come outside the house and look that I connected the dots.
    The epicenter of the explosion happened 20 km east of where I was living 30000 feet in the air.
    The space rock, whatever it was, was never found and probably all of it disintegrated in the air.
    The pictures in that video is very similar to what the cloud looked like that I saw at time.

  36. I am baffled as to how a hot, fast moving rock the size of a small house can explode with the force of an atomic bomb. Sure, I realize that there is a lot of kinetic and thermal energy there, but c’mon, rock is hardly an energetic material, its not like it was 50 kilotons of TNT or anything.
    Could someone please enlighten this poor benighted soul?

  37. I believe that many asteroids are not very dense, and are loose agglomerations of rocks and ice. If one of these hits an atmosphere, it will break up quite quickly.
    There is a theory with some observational evidence that quite large but diffuse ‘snowball’ objects are hitting the atmosphere frequently, and just dissipating at a very high altitude, adding to the planet’s supply of water. But there’s no money to carry out a search for them….
    There are a few nickel-iron asteroids, which, presumably, are quite dense. If a small one of these – say, 40m diameter, were to impact the atmosphere I suspect it would survive to hit the ground. And if this were in a city like Bombay, the most populous city in the world….

  38. I always believe we were very fortunate that one of these explosions didn’t trigger a crisis during the cold war.
    Imagine an asteroid explosion over one of our major cities during the Cuban Missile Crisis. Would we have struck back at the Soviets before we determined it was a natural event? The Soviets might very well have done so if it happened to them.
    BTW: A large comet or asteroid impact can cause immediate climate change on a world-wide scale!

  39. Someone (perhaps a Socialogist or Economist – anyway somone with impecable credentials) should generate a computer simulation to absolutely “prove” that NEO’s are the biggest cause of global warming and the horrific rise we have witnessed in CO2 levels since the end of the Little Ice Age bar none. The closer they get to earth the more they bleed thir putrid chemicals into our pristine atmosphere. AND, that “Cap and Trade” legislation must be passed immideately to offset the tremendous expense to the advanced nations of fighting this terrible menace for mankind and civilization. This is something Al Gore should pick up and run with immediately. Why hasn’t he done so? What is he waiting for?

  40. Enduser (06:21:37) :
    I am baffled as to how a hot, fast moving rock the size of a small house can explode with the force of an atomic bomb. Sure, I realize that there is a lot of kinetic and thermal energy there, but c’mon, rock is hardly an energetic material, its not like it was 50 kilotons of TNT or anything.
    Could someone please enlighten this poor benighted soul?

    It would be during the break up phase you have all that kinetic energy converted to heat very rapidly. While the object is in one piece it is heating a long column of atmosphere as it burns up. If at some point the object suddenly comes apart into thousands of smaller pieces, the frontal area of all those objects is much larger than the frontal area of the original piece. As a result the rate energy is deposited in the atmosphere goes up very rapidly, so instead of converting the kinetic energy into heat over a period of time, almost all the kinetic energy is converted to heat in a very short period of time.
    It is just a time rate of energy release situation. That raises a very large volume of the atmosphere to very high temperatures in a very short period of time. It is the expansion of that ball (pancake) of super heated air that causes the explosive effect.
    Larry

  41. John Galt (06:33:18) :
    I always believe we were very fortunate that one of these explosions didn’t trigger a crisis during the cold war.

    It came close a couple of times, the satellites designed to look for the flash signatures or nuclear weapons bursts and the exhaust heat plumes of rocket launches witnessed some of these high altitude explosions and were for a time investigated as possible surreptitious nuclear tests. That was when science began to realize how common such energetic atmospheric impacts were, and that many of them occur over oceans or uninhabited parts of the earth during day light and are never noticed by the public at large.
    It is only the large fire ball /bolides that hit in populated areas during the dark of night that usually get noticed. When you realize how small a fraction of the earths surface high density human occupation covers compared to the open oceans and barren desert/mountain areas, these are a lot more frequent than many people suspect.
    Larry

  42. I suppose a carbonaceous asteroid could produce a fuel-air bomb in addition to its kinetic energy. Double ouch!

  43. To facilitate an understanding of the magnitude of the kinetic energy, consider this notional example:
    The volume of a 10-meter diameter object (spherical) is 523.6 cubic meters. If the material is similar to rock (~specific gravity of 2), the total mass will be slightly over 1 million kilograms.
    If the object is traveling relative to the Earth at 30 km/sec (a low to middling speed for meteors), the kinetic energy (found from 1/2 mv^2) is 4.7 x 10^14 joules. The energy equivalent of 1 kT TNT is 4.184 x 10^12 joules, which places the kinetic energy of the meteor at 112.6 kT equivalent.
    This is high relative to the news item, but in the ballpark. I have been in the business of designing kinetic energy weapons. At a sufficient speed, pure mass is far more energetic upon collision than TNT is upon explosion.
    At least a massive meteor will produce no radiation or radioactivity!

  44. As Michael J pointed out, the key is in the speed. My question though is this:
    A very small object will be attenuated very sharply by the earth’s atmosphere, so will strike the ground with a low velocity. As the mass increases less speed will be lost. Does anyone have a ballpark figure for the kind of mass necessary to allow impact speeds to be close to the original speed?

  45. “At least a massive meteor will produce no radiation or radioactivity!” Michael
    What about one from outside the Solar System? How fast would it have to go?

  46. Layne Blanchard (20:00:27) : “I had the opportunity as a young boy to observe a large object pass over the Lake Tahoe area.”
    I saw one in the late ’50s while visiting the ancestral family farm in Iowa. Just after dark, seemingly close overhead, but silent with no visible trail. Probably skimmed the atmosphere and left.
    In daylight I assume it would have looked a lot like this:

  47. To Vincent’s question:
    “A very small object will be attenuated very sharply by the earth’s atmosphere, so will strike the ground with a low velocity. As the mass increases less speed will be lost. Does anyone have a ballpark figure for the kind of mass necessary to allow impact speeds to be close to the original speed?”
    Actually, it doesn’t turn out that way. The key parameter determining deceleration is the ballistic coefficient, which is related to the mass per unit area of the approaching object (and also to the drag coefficient, but we will take that as a constant across all spheroidal objects). For a constant density, mass increases with the cube of the diameter but frontal area increases with the square of the diameter. This means that larger objects will have larger ballistic coefficients and will decelerate less. And faster objects (say 70 km/sec) will have so much kinetic energy, that the relative deceleration may be minor. But you have to work out the numbers.
    An excellent scale example is the Barringer Meteor Crater in Arizona (http://en.wikipedia.org/wiki/Meteor_crater) which was characterized as being comprable to a 5-10 megaton nuclear surface detonation. The impact object is estimated to have been 50 meters in diameter.
    To Back2Bat’s question:
    “What about one from outside the Solar System? How fast would it have to go?” [to produce radiation/radioactivity?]
    I don’t know what you are asking exactly, but (a) asteroids are solar system objects, not interstellar objects, (b) any interstellar object would arrive in our vicinity at or above the local solar system escape velocity (about 617.5 km/sec; it would take 20 seconds to transit the Earth’s diameter), and (c) there’s nothing in this that results in nuclear physics (unless the impact temperature is high enough to enable thermonuclear reactions).

  48. Layne, Fluffy, what you saw were touch-and-go incidents, much like the effect of skipping a stone across water. If the impact angle is sufficiently oblique, the NEO will indeed return to space without impact or explosion. It’s common enough to have been photographed on several occasions. And, for the curious, the “skipper” need not be flat, as the Brits demonstrated with their dam-busters during WWII.

  49. “(c) there’s nothing in this that results in nuclear physics (unless the impact temperature is high enough to enable thermonuclear reactions).” Michael J Dunn
    Thanks for the info. Yes, that was my question; how fast would an object have to impact to cause thermonuclear reactions? I have a morbid curiosity about explosions, I guess.
    BTW, Vincent said what you said but with less precision. He deserves partial credit, don’t you think?

  50. Back2Bat (11:03:56) :
    “At least a massive meteor will produce no radiation or radioactivity!” Michael
    What about one from outside the Solar System? How fast would it have to go?

    As CuriousGeorge has already posted above ( Curiousgeorge (18:53:56) : ), check out the interactive calculator at . http://www.lpl.arizona.edu/impacteffects/
    This calculator answers some of those questions in the body of the web page.

    The minimum impact velocity on Earth is 11 km/s. Typical impact velocities are 17 km/s for asteroids and 51 km/s for comets. The maximum Earth impact velocity for objects orbiting the sun is 72 km/s.

    It also includes a PDF that is interesting reading of more detailed information about impactors.
    http://www.lpl.arizona.edu/impacteffects/CollinsEtAl2005.pdf
    In that paper on page 4 (numbered 820 in the pdf) it explains that the important parameter is the ratio between the mass of the object and the mass of atmosphere it will displace during entry. When the bodies mass is much greater than the displaced atmosphere you can largely ignore the atmospheric braking process.

    “Atmospheric entry has no significant influence on the shape, energy, or momentum of impactors with a mass that is much larger than the mass of the atmosphere displaced during penetration.”

    The full PDF is worth reading!
    Larry

  51. Apologies to Vincent; I misread what he wrote. Either too much or too little coffee today. Sorry.
    As for thermonuclear temperatures, we can estimate by calculating the specific kinetic energy of ~600 km/sec as being 1.8 x 10^11 joules/kg. If the asteroid is composed of (e.g.) iron (atomic weight = 56 grams/mole), this gives us about 1.67 x 10^-14 joules/molecule. This can be equated to thermal energy as 3/2 kT, where Boltzmann’s constant (k) is 1.38 x 10^-23 joules/kelvin, giving a temperature T = 1.2 billion degrees. This is in the ballpark for some fusion reactions (e.g., deuterium-deuterium)…but there is no possibility of any fusion occurring for anything made of iron, or other “heavy” elements (meaning heavier than the isotopes of hydrogen).
    Consider the craters of the Moon and thank God we are not afflicted with such events.
    Might be interesting to investigate whether periodic massive changes in climate are synchronized with recurrent, massive meteor bombardment events.

  52. Michael J. Dunn (09:00:58) :
    To facilitate an understanding of the magnitude of the kinetic energy, consider this notional example:
    _________________________________
    Outstanding answers and discussion, gentlemen! All of you that weighed in are appreciated. The prize, if there was one, would have to go to Mr. Dunn.
    Honorable mentions to Hotrod and Backtobat.
    Thank you!

  53. As for thermonuclear temperatures, we can estimate by calculating the specific kinetic energy of ~600 km/sec as being 1.8 x 10^11 joules/kg. Michael J Dunn
    Thanks for those calcs. I really wish I had paid more attention in physics.
    I guess there is little danger of Jupiter blowing up from an extra-solar system meteor strike?

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