it's not exactly reasoned debate - and this [Deayton's history] would have amounted to a get-out-of-jail-free card for guests.
. . . which would have exposed the stupidity (or inebriation) the guests who don't pick up their GOoJF card.
Having the show run on that basis in the long run would have robbed it of most of its impact.
Oh, I don't know ; I enjoyed seeing Merton put the (be-cramponned) boot into Deayton. A more justifiable bloodsport than fox hunting, and you can do it again next week. Cross-reference : Stephen Fry feasting on Alan Davies' liver every week.
In the climate change realty we face there is NO IMMINENT DANGER
... to me, the danger of being kidnapped at work by Somali pirates is much more real and imminent. Climate change isn't terribly worrying to me - I earn enough to afford to eat, and have an environmental tolerance that extends between the deserts of the Arabian Peninsula to winter in Siberia (or Newfoundland), so I don't have any worries about that.
So that leaves concerns about the children. I don't give a shit what you think about my non-existent children, and I sure as hell don't give a shit what is going to happen to your children, let alone grandchildren (if your children are stupid enough to not use contraception). So that's all right then. No problems.
Feel free to fill up your SUV's tank - you're pouring money indirectly into my pocket, and I'm not complaining.
So by "blowing up" I mean "drop the temperature by 20 degrees", which would basically start a new ice age.
It would probably only take in the order of 5 degrees (Kelvin ; you didn't specify). But it would probably take several centuries to develop a full-blown ice age, as opposed to dropping temperatures enough to allow large areas to start accumulating snow from winter to winter (thus triggering positives feedbacks).
If done with aerosols, once this starts, it's unstoppable.
That depends on the half-life of your aerosol in the atmosphere. Which varies for the aerosol chosen and the height they're injected into the atmosphere at.
Observation of volcanically-injected sulphate into the middle atmosphere (principally the Pinatubo experiment) suggests that the half-life of that aerosol in that part of the atmosphere is around a year. And for other aerosols, and other parts of the atmosphere?
That question implies experimentation. Which I'd probably support. That is not the same as supporting putting this geoengineering scheme into action.
Generally deep sea stuff tends to explode once we bring it up due to pressure differential.
Equally, shallow-sea stuff (humans adapted to 0m +/-1.5m water depth) tends to collapse once taken to more than 10m depth if compressed rapidly enough and to leak bodily fluids if taken rapidly to high altitudes.
Almost everything doesn't like rapid pressure changes. Many organisms however can withstand considerable changes of pressure over a fair duration.
Actually, I can extend that to inorganic materials too : standard procedure for handling rock cores in the drilling industry is to pull from coring depth to 20 stands (typically 30m/stand, but it varies) at [as fast as possible, within the well's swab/surge limits and the power available] ; then from 20 to 10 stands at 5 minutes/stand ; 10 minutes/stand for the next 5 stands ; 20 minutes per stand for the last 5 stands (by which time you're often catching core anyway). These time consuming operations (think : USD 500/ minute base cost, plus specialists) are all about getting samples to surface with less de-pressurisation damage.
When deep-sea organisms come up to the surface under their own timetable, they're all capable of coming up without damage. Which is why we get regular examples of, for example, giant squid stranded on beaches, but anatomically more-or-less intact (this doesn't address the question of what caused the squid, for example, to beach).
If you take your time, it is perfectly possible to bring deep-sea specimens "up to surface", or "down to surface pressure" as my saturation diver friends would put it (while spending a week coming "to surface" out of a pressure chamber which is physically on the surface). But time costs money, so there is always a conflict between achieving sampling aims and getting the cruise completed.
And before you raise the question, yes, whales and seals are remarkably adapted to handle the pressure changes in their lives. Remarkably adapted, from their blood outwards.
It's a single-celled organism, allegedly, but I don't necessarily see that as being the same as "simple". The biochemical complexity of some of the smallest of bacteria is still very high, while some of the largest of viruses (mimivirus et al), which one would expect to be "simple", have genomes considerably larger than some "complex" bacteria.
The story is rather light on detail, but the location given is along strike from the location of the Solnhofen limestone outcrops and quarries that have yielded (amongst others), the specimens of Archaeopteryx.
IF this is an appropriate correlation, then the environment of deposition is likely to have been an intermittently stratified and anoxic lagoon of brackish water with active deposition of (phytoplanktonic) carbonate. Storm- or flood-driven overturning events are thought to have lead to intermittent depletion of oxygen in surface waters, leading to occasional mass-death events in the marine fossils, which then sink to the seabed which rapidly returns to being anoxic. bodies that fall to the sea floor are slowly buried in very anoxic limestone mud. The most important point is not the mineralogy of the sediment, but it's fine grain size.
That's a first-cut description of the environment of the Solnhofen area, and it's no great stretch to extend 50-odd km. Time (135Ma BP) is suitable too.
Concerning the issues some people raise about the ownership of the specimen... "Meh". The locals don't express any great concerns over the issue, and certainly don't seem to be expressing any desire to replace their functioning federated law system with a foreign one based on a different interpretation of "right behavior".
Sounds a nice specimen - better than most of the Archy specimens.
(Incidentally, the recent Chinese bird fossil gold mine has come from another anoxic fresh-to brackish lake environment. The precise dating is a little more recent than for Solenhofen, but some formations are probably somewhat older. So really, we're looking for an "Urvogel" somewhat earlier than Archy and probably a 3-way intermediate between Archy, the Chinese "dragons", and an early maniraptorean theropod. Until we find that "Urvogel", at which point we start looking for three more "intermediate fossils")
I just don't understand why a US based mega-corporation would help Iranians secure they weapon of m*** destruction?
One word answer : money. Any mega-corp, and most midi- and mini- corps, will do pretty much anything for money. It's in the nature of being in business.
Odds of successfully detecting an incoming "city killer" - very small. Yes, I'd go with that. I'd add the rider that we've got a better handle on the near-future probability of a "continent killer" as being fairly low.
To extend what surveying we do to cover high inclinations to the ecliptic would be a major undertaking. Which would be expensive, very expensive. Would we get better service from (say) spending that money on attempting to eradicate malaria? Quite possibly.
Much of the data analysis would be capable of being automated, but there will be events that can't be filtered out automatically because we simply don't understand what they are. Those will need some degree of manual study, until they are well enough understood that they can be filtered out automatically. And the flow of data will be huge, so the number of false positives will be high.
The link I cited for USAF data suggests around one significant airburst per month. I don't think we have enough data to put a number on the rate of actual impactors. I would suspect that these days the assumption on detection of a large explosion is that it's an airburst meteorite, not a nuclear explosion. Though the systems were designed for detecting nuclear explosions, it's an interesting serendipity that they're mainly detecting something else. Gamma Ray Bursters, anyone?
Though I don't know what actual procedures are in place in the CTBT monitoring, I'd only consider a nuke as a credible explanation in a small number of geographical regions - DPRK, Israel, possibly Western China, Iran ; anywhere else, I'd start from the assumption that an explosion was a meteorite. Then, as data came in (radio-isotope data, seismic) that might get revised.
I transferred some cash to BitCoins and back on Friday and it was paid out to me on Sunday. By the time I got the transfer, it had lost almost half of its value. Now imagine if that would constantly happen with your real money.
And just how is this is different to any two other currencies? It's a problem that any multiple-currency transactions face.
Having just completed last months expenses claim, in three currencies, with a requirement from BeanCounter Central that every transaction have the exchange rate for that day included in the calculation... the fluctuation of one currency against another is absolutely normal.
Is this news to you? Why? Have you never dealt with currency transactions before?
I think you'd still be dealing with the receptionist, who doesn't know you, know anything, and whose job is to deal with cranks, politely.
Crank calls - and honest mistakes - will happen and will find any "access point" well-enough publicised to actually be useful to Joe Random Astronomer in his dome. So there will be PR flacks that you'll have to get through.
So, unless some group is being specifically employed to carry out searches like this, and have a particular phone line to the appropriate powers... I don't see it working. (Yes, several navies etc have astronomical services. Most of these are for producing navigational ephimerides, not observational work. Those observations that are done, are focussed on (specifically, for the USNO) ecliptic surveys for NEOs and PHAs, not on performing the multiple-fold whole-sky continuous survey that you're implying.
It's not impossible to do this ; but it's not being done (AFAIK).
There are robotic whole-sky surveys. But they have limiting magnitudes in the 8 or 9 range. For the sort of detections you're talking about, you'll need to go down to magnitude 15 or more. That's a major leap of technology and probably optics.
What's the data processing pipeline for that sort of project going to be like? Say... a 6 hour imaging cycle... you'll need to get to something like arc-second resolution, so that's 839,808,000,000 pixels for the whole sky. You're going to have to align successive images (actually, you'd do it by tiles, but WTF), compare them for differences, then detect the interesting events.
Define "interesting" : if I've got my maths correct, you're looking at something 600+ times the coverage of the Kepler mission, though possibly with lower dynamic range. They've got 24 planet candidates, 2176 eclipsing binaries, and who knows how much other stuff. And you've got to sort out your incoming impactor from this lot. In a real-time setting.
Not as trivial as it sounds, is it? You'd probably need to build an astronomical university just to train enough astronomer-technicians to weed out the false positives.
Be a fun project though. Real fun. Make that LHC thing look like the small science it is.
Also, wouldn't it be relatively easy to figure out where this thing was headed and find out where it is now?
"relatively easy" for certain values of "easy" starting at "extremely difficult" and extending towards the impossible.
Firstly, the records are pretty sparse ; effectively we've only got two putative measurement points, and each of those has an accuracy of less than a half-degree (the angular size of the sun). IF (and it is a real "if") there exists a possible Keplerian solution for such an object that fits with the records, then that orbit will be quite imprecise precisely because we don't know where the centre of mass of the object was, merely that some of the particles were within the half-degree area of the Sun's disc. Pick your model for where the centre of mass is - I'd probably start by modelling the first estimates for the centre of mass to lay on a circle of a degree in diameter, concentric with the solar disc - work out the range of Keplerian solutions for each pair of possible observations (say, 4 points at each observation, for 16 possible orbits)
Oh, now you've got 16 possible orbits. But that's still "relatively easy".
How close do these orbits approach the Earth? Because that is going to severely affect the amount by which the orbit is perturbed, both going forward and backwards in time. You're going to face this problem every time the orbit approaches that of the Earth. And the Moon. And the rest - the orbit-tracking code that the MPC uses includes the effects of all the planets, satellites and some of the larger asteroids. (MPC - Minor Planets Centre, the clearing house for observations of minor planets, including potential hitters. Oh, they've moved websites : http://minorplanetcenter.net/iau/mpc.html )
It all gets literally chaotic, very rapidly.
The absence of other observations of cometary fragments around this time is strong evidence that there wasn't a close approach by a comet then. It may not have been as widely discussed a topic then as today (walk down the street today and find how many people know what a "Potentially Hazardous Asteroid" is ; you won't find many people who know, or care), but some people certainly knew what the potential of an impact was, in general terms. The 1910 apparition of Halley's comet was accompanied by significant media hysteria about the closeness of the comet to the Earth. I don't think it credible that 22 years previously, not one person put two and two together to report on an unusual coincidence of comets. Having Hyakutake and Hale-Bopp so close together excited noticeable attention a couple of years ago ; imagine actually having two comets extremely close together in time and in the sky, and moving extremely fast (because they're nearby) - how much attention would that have gathered. Remember too, that this was a time when light pollution was much less extensive.
The observations were repeated on successive days. Given the length of night at that site and the time of year, that means that they were at least 13 hours from start of first observation to end of last observation. Because the observatory passed through the night between observations, and the (alleged) comet was between the observatory and the sun... then every observatory on the antipodal side of the planet to the observatory was better placed than this observatory.
The reported observations were from Mexico City (approximately). The antipode is around the India - Indonesia - East Africa longitude (the 13 hour implied duration also implies an arc of at least 195 degrees which passed through the sub-solar point, and therefore through the sub-cometary point). Not the most highly developed of areas, particularly at that time, but with significant historical activity in astronomy. So I'd be pretty surprised if there were no active observers at the time.
You do of course also have to replace a PC every few years if that's your development platform.
A while ago I read an article by a well-respected technology pundit about his equipment upgrade plans for his sandpit of developers. His reckoning was that it didn't become worthwhile going through the disruption of an upgrade cycle until the new generation of hardware had 3 times the [metric] of the old hardware. (For [metric] meaning processor speed, or hard drive size, or memory capacity, or bandwidth or...) The topic at the time was why he wasn't going to be replacing his developers 20MHz 386 machines with the newer, shinier 25MHz 386s ; the author was "Doc Solly" of the Dr Solomon's anti-virus suite and he was talking about a pretty cutting-edge sandpit of developers. Someone who does actually know what he's talking about.
All of which made pretty good sense to me - fuck the "shiny" aspects of things and replace hardware when new hardware will have a SIGNIFICANT effect on your productivity, and don't forget to account for the reduced productivity inherent during periods of change. If Moore's law is valid, you'd be replacing things on about a 3 year cycle, but it depends significantly on what you consider your important metric. Our (my employer's) code-jockeys don't generally find the code is processor bound, but are limited by database access speed. So we generally don't bother too much about the latest lump of silicon from a chip company, but we do look for fast access times in hard drives.
But in general, replace hardware when it's going to be useful, not on a fixed cycle. (Which is advice that will have hardware vendors spitting with rage.)
(There are complicating factors ; for us, the rules about amortization of capital assets does peculiar things with the tax man, and changes the detailed plans. But we have bean counters to worry about that, not humans.)
We've had one example so far of a natural object being spotted far enough in advance for it's impact to be predicted and localised. One example.
Meanwhile, the military are seeing multiple airbursts yearly (from http://meteor.uwo.ca/~pbrown/usaf.html I'm seeing around one event a month, on a rough average) in the multi-Hiroshima range of energy release.
This does not inspire me with confidence that an incoming bolide will be detected as such. It is possible that such a detection would occur ; the probability of such a detection occuring may be increasing ; but I don't think we're "there" yet.
On the other hand, the census of potentially regionally-devastating NEOs (Near-Earth Objects) is steadily improving, so for events that are likely to kill billions, we're getting some better odds of knowing about it in advance, even if we don't (yet) have anything we can do about it. But this census has a severe limitation : it's focussed on objects in regular planet-like orbits, and therefore on objects near the ecliptic. But we also know that there is another class of potential impactor - the long-period and single-apparition comets, and they can come from literally any direction. Which makes spotting them before the event rather more challenging.
As a geologist who has been sent to work in Siberia, and who intends to get paid to go there again, I take a non-trivial interest in the Tunguska event (despite not having got closer to the site than a couple of thousand km. Yet.). I've not heard of any evidence for the nature of the presumed impactor. Evidently you have. Citation please.
One point to remember (quoting from the 1963 Meteorica report) : "Under field conditions it is precisely the magnetic spheres that most readily lend themselves to concentration and identification."
The impactor at Barringer Crater (Meteor Crater) somewhere in America was on the order of 50 to 100m across. The crater is bigger than any nuclear test crater that I've heard of.
If we could sequester the majority of that CO2 as happened on Earth and added a bit of a sun shade, then yes, Venus would be more hospitable than Mars. Once you solve those tiny inconveniences.
Well... the sun shade is large engineering, but fundamentally nothing terribly new. Self-steering solar sails at the L1 point, keep on adding them until you've reduced the irradiation to your desired level.
Too much atmosphere? Throw rocks at it until you've blown enough away. Take care to not hit nearby occupied planets.
Genetically engineering carbon-fixing bacteria that can live at the cloud tops might be safer (for the nearby planets), and might well be easier.
Slashdot Mirror
Ref. previous comment about Stephen Fry Promethean relationship with Alan Davies on QI.
. . . which would have exposed the stupidity (or inebriation) the guests who don't pick up their GOoJF card.
Oh, I don't know ; I enjoyed seeing Merton put the (be-cramponned) boot into Deayton. A more justifiable bloodsport than fox hunting, and you can do it again next week. Cross-reference : Stephen Fry feasting on Alan Davies' liver every week.
One of the weirdest insults I've ever seen. If it was an insult ; even that isn't clear.
But what else would you expect from an AC? They rarely rise to the level of American Retard Reject.
So that leaves concerns about the children. I don't give a shit what you think about my non-existent children, and I sure as hell don't give a shit what is going to happen to your children, let alone grandchildren (if your children are stupid enough to not use contraception). So that's all right then. No problems.
Feel free to fill up your SUV's tank - you're pouring money indirectly into my pocket, and I'm not complaining.
Energy crisis? What energy crisis?
Which part of the word "experiment" do you not understand? And you a Slashdot reader?
It would probably only take in the order of 5 degrees (Kelvin ; you didn't specify). But it would probably take several centuries to develop a full-blown ice age, as opposed to dropping temperatures enough to allow large areas to start accumulating snow from winter to winter (thus triggering positives feedbacks).
That depends on the half-life of your aerosol in the atmosphere. Which varies for the aerosol chosen and the height they're injected into the atmosphere at.
Observation of volcanically-injected sulphate into the middle atmosphere (principally the Pinatubo experiment) suggests that the half-life of that aerosol in that part of the atmosphere is around a year. And for other aerosols, and other parts of the atmosphere?
That question implies experimentation. Which I'd probably support. That is not the same as supporting putting this geoengineering scheme into action.
Mod parent down. He's talking boring reality, not exciting fantasy.
... leading directly to toxic waste dumps full of dead Monsanto [insert transnational organism of choice] executives. Net gain - near zero.
Equally, shallow-sea stuff (humans adapted to 0m +/-1.5m water depth) tends to collapse once taken to more than 10m depth if compressed rapidly enough and to leak bodily fluids if taken rapidly to high altitudes.
Almost everything doesn't like rapid pressure changes. Many organisms however can withstand considerable changes of pressure over a fair duration.
Actually, I can extend that to inorganic materials too : standard procedure for handling rock cores in the drilling industry is to pull from coring depth to 20 stands (typically 30m/stand, but it varies) at [as fast as possible, within the well's swab/surge limits and the power available] ; then from 20 to 10 stands at 5 minutes/stand ; 10 minutes/stand for the next 5 stands ; 20 minutes per stand for the last 5 stands (by which time you're often catching core anyway). These time consuming operations (think : USD 500/ minute base cost, plus specialists) are all about getting samples to surface with less de-pressurisation damage.
When deep-sea organisms come up to the surface under their own timetable, they're all capable of coming up without damage. Which is why we get regular examples of, for example, giant squid stranded on beaches, but anatomically more-or-less intact (this doesn't address the question of what caused the squid, for example, to beach).
If you take your time, it is perfectly possible to bring deep-sea specimens "up to surface", or "down to surface pressure" as my saturation diver friends would put it (while spending a week coming "to surface" out of a pressure chamber which is physically on the surface). But time costs money, so there is always a conflict between achieving sampling aims and getting the cruise completed.
And before you raise the question, yes, whales and seals are remarkably adapted to handle the pressure changes in their lives. Remarkably adapted, from their blood outwards.
It's a single-celled organism, allegedly, but I don't necessarily see that as being the same as "simple". The biochemical complexity of some of the smallest of bacteria is still very high, while some of the largest of viruses (mimivirus et al), which one would expect to be "simple", have genomes considerably larger than some "complex" bacteria.
IF this is an appropriate correlation, then the environment of deposition is likely to have been an intermittently stratified and anoxic lagoon of brackish water with active deposition of (phytoplanktonic) carbonate. Storm- or flood-driven overturning events are thought to have lead to intermittent depletion of oxygen in surface waters, leading to occasional mass-death events in the marine fossils, which then sink to the seabed which rapidly returns to being anoxic. bodies that fall to the sea floor are slowly buried in very anoxic limestone mud. The most important point is not the mineralogy of the sediment, but it's fine grain size.
That's a first-cut description of the environment of the Solnhofen area, and it's no great stretch to extend 50-odd km. Time (135Ma BP) is suitable too.
Concerning the issues some people raise about the ownership of the specimen ... "Meh". The locals don't express any great concerns over the issue, and certainly don't seem to be expressing any desire to replace their functioning federated law system with a foreign one based on a different interpretation of "right behavior".
Sounds a nice specimen - better than most of the Archy specimens.
(Incidentally, the recent Chinese bird fossil gold mine has come from another anoxic fresh-to brackish lake environment. The precise dating is a little more recent than for Solenhofen, but some formations are probably somewhat older. So really, we're looking for an "Urvogel" somewhat earlier than Archy and probably a 3-way intermediate between Archy, the Chinese "dragons", and an early maniraptorean theropod. Until we find that "Urvogel", at which point we start looking for three more "intermediate fossils")
One word answer : money. Any mega-corp, and most midi- and mini- corps, will do pretty much anything for money. It's in the nature of being in business.
Why is it difficult to understand this?
To extend what surveying we do to cover high inclinations to the ecliptic would be a major undertaking. Which would be expensive, very expensive. Would we get better service from (say) spending that money on attempting to eradicate malaria? Quite possibly.
Much of the data analysis would be capable of being automated, but there will be events that can't be filtered out automatically because we simply don't understand what they are. Those will need some degree of manual study, until they are well enough understood that they can be filtered out automatically. And the flow of data will be huge, so the number of false positives will be high.
The link I cited for USAF data suggests around one significant airburst per month. I don't think we have enough data to put a number on the rate of actual impactors. I would suspect that these days the assumption on detection of a large explosion is that it's an airburst meteorite, not a nuclear explosion. Though the systems were designed for detecting nuclear explosions, it's an interesting serendipity that they're mainly detecting something else. Gamma Ray Bursters, anyone?
Though I don't know what actual procedures are in place in the CTBT monitoring, I'd only consider a nuke as a credible explanation in a small number of geographical regions - DPRK, Israel, possibly Western China, Iran ; anywhere else, I'd start from the assumption that an explosion was a meteorite. Then, as data came in (radio-isotope data, seismic) that might get revised.
And just how is this is different to any two other currencies? It's a problem that any multiple-currency transactions face.
Having just completed last months expenses claim, in three currencies, with a requirement from BeanCounter Central that every transaction have the exchange rate for that day included in the calculation ... the fluctuation of one currency against another is absolutely normal.
Is this news to you? Why? Have you never dealt with currency transactions before?
Crank calls - and honest mistakes - will happen and will find any "access point" well-enough publicised to actually be useful to Joe Random Astronomer in his dome. So there will be PR flacks that you'll have to get through.
So, unless some group is being specifically employed to carry out searches like this, and have a particular phone line to the appropriate powers ... I don't see it working. (Yes, several navies etc have astronomical services. Most of these are for producing navigational ephimerides, not observational work. Those observations that are done, are focussed on (specifically, for the USNO) ecliptic surveys for NEOs and PHAs, not on performing the multiple-fold whole-sky continuous survey that you're implying.
It's not impossible to do this ; but it's not being done (AFAIK).
There are robotic whole-sky surveys. But they have limiting magnitudes in the 8 or 9 range. For the sort of detections you're talking about, you'll need to go down to magnitude 15 or more. That's a major leap of technology and probably optics.
What's the data processing pipeline for that sort of project going to be like? Say ... a 6 hour imaging cycle ... you'll need to get to something like arc-second resolution, so that's 839,808,000,000 pixels for the whole sky. You're going to have to align successive images (actually, you'd do it by tiles, but WTF), compare them for differences, then detect the interesting events.
Define "interesting" : if I've got my maths correct, you're looking at something 600+ times the coverage of the Kepler mission, though possibly with lower dynamic range. They've got 24 planet candidates, 2176 eclipsing binaries, and who knows how much other stuff. And you've got to sort out your incoming impactor from this lot. In a real-time setting.
Not as trivial as it sounds, is it? You'd probably need to build an astronomical university just to train enough astronomer-technicians to weed out the false positives.
Be a fun project though. Real fun. Make that LHC thing look like the small science it is.
"relatively easy" for certain values of "easy" starting at "extremely difficult" and extending towards the impossible.
Firstly, the records are pretty sparse ; effectively we've only got two putative measurement points, and each of those has an accuracy of less than a half-degree (the angular size of the sun). IF (and it is a real "if") there exists a possible Keplerian solution for such an object that fits with the records, then that orbit will be quite imprecise precisely because we don't know where the centre of mass of the object was, merely that some of the particles were within the half-degree area of the Sun's disc. Pick your model for where the centre of mass is - I'd probably start by modelling the first estimates for the centre of mass to lay on a circle of a degree in diameter, concentric with the solar disc - work out the range of Keplerian solutions for each pair of possible observations (say, 4 points at each observation, for 16 possible orbits)
Oh, now you've got 16 possible orbits. But that's still "relatively easy".
How close do these orbits approach the Earth? Because that is going to severely affect the amount by which the orbit is perturbed, both going forward and backwards in time. You're going to face this problem every time the orbit approaches that of the Earth. And the Moon. And the rest - the orbit-tracking code that the MPC uses includes the effects of all the planets, satellites and some of the larger asteroids. (MPC - Minor Planets Centre, the clearing house for observations of minor planets, including potential hitters. Oh, they've moved websites : http://minorplanetcenter.net/iau/mpc.html )
It all gets literally chaotic, very rapidly.
The absence of other observations of cometary fragments around this time is strong evidence that there wasn't a close approach by a comet then. It may not have been as widely discussed a topic then as today (walk down the street today and find how many people know what a "Potentially Hazardous Asteroid" is ; you won't find many people who know, or care), but some people certainly knew what the potential of an impact was, in general terms. The 1910 apparition of Halley's comet was accompanied by significant media hysteria about the closeness of the comet to the Earth. I don't think it credible that 22 years previously, not one person put two and two together to report on an unusual coincidence of comets. Having Hyakutake and Hale-Bopp so close together excited noticeable attention a couple of years ago ; imagine actually having two comets extremely close together in time and in the sky, and moving extremely fast (because they're nearby) - how much attention would that have gathered. Remember too, that this was a time when light pollution was much less extensive.
The reported observations were from Mexico City (approximately). The antipode is around the India - Indonesia - East Africa longitude (the 13 hour implied duration also implies an arc of at least 195 degrees which passed through the sub-solar point, and therefore through the sub-cometary point). Not the most highly developed of areas, particularly at that time, but with significant historical activity in astronomy. So I'd be pretty surprised if there were no active observers at the time.
A while ago I read an article by a well-respected technology pundit about his equipment upgrade plans for his sandpit of developers. His reckoning was that it didn't become worthwhile going through the disruption of an upgrade cycle until the new generation of hardware had 3 times the [metric] of the old hardware. (For [metric] meaning processor speed, or hard drive size, or memory capacity, or bandwidth or ...) The topic at the time was why he wasn't going to be replacing his developers 20MHz 386 machines with the newer, shinier 25MHz 386s ; the author was "Doc Solly" of the Dr Solomon's anti-virus suite and he was talking about a pretty cutting-edge sandpit of developers. Someone who does actually know what he's talking about.
All of which made pretty good sense to me - fuck the "shiny" aspects of things and replace hardware when new hardware will have a SIGNIFICANT effect on your productivity, and don't forget to account for the reduced productivity inherent during periods of change. If Moore's law is valid, you'd be replacing things on about a 3 year cycle, but it depends significantly on what you consider your important metric. Our (my employer's) code-jockeys don't generally find the code is processor bound, but are limited by database access speed. So we generally don't bother too much about the latest lump of silicon from a chip company, but we do look for fast access times in hard drives.
But in general, replace hardware when it's going to be useful, not on a fixed cycle. (Which is advice that will have hardware vendors spitting with rage.)
(There are complicating factors ; for us, the rules about amortization of capital assets does peculiar things with the tax man, and changes the detailed plans. But we have bean counters to worry about that, not humans.)
Meanwhile, the military are seeing multiple airbursts yearly (from http://meteor.uwo.ca/~pbrown/usaf.html I'm seeing around one event a month, on a rough average) in the multi-Hiroshima range of energy release.
This does not inspire me with confidence that an incoming bolide will be detected as such. It is possible that such a detection would occur ; the probability of such a detection occuring may be increasing ; but I don't think we're "there" yet.
On the other hand, the census of potentially regionally-devastating NEOs (Near-Earth Objects) is steadily improving, so for events that are likely to kill billions, we're getting some better odds of knowing about it in advance, even if we don't (yet) have anything we can do about it. But this census has a severe limitation : it's focussed on objects in regular planet-like orbits, and therefore on objects near the ecliptic. But we also know that there is another class of potential impactor - the long-period and single-apparition comets, and they can come from literally any direction. Which makes spotting them before the event rather more challenging.
Evidently he (or she) is assuming something like that.
Depressingly, s/he is probably right to make that assumption.
Fortunately, my children won't have to live through the hellish conditions that this behaviour will bring about.
Citation please?
As a geologist who has been sent to work in Siberia, and who intends to get paid to go there again, I take a non-trivial interest in the Tunguska event (despite not having got closer to the site than a couple of thousand km. Yet.). I've not heard of any evidence for the nature of the presumed impactor. Evidently you have. Citation please.
One point to remember (quoting from the 1963 Meteorica report) : "Under field conditions it is precisely the magnetic spheres that most readily lend themselves to concentration and identification."
The Perseids (meteor shower) peak around then.
Doesn't sound terribly unlikely to me.
Well ... the sun shade is large engineering, but fundamentally nothing terribly new. Self-steering solar sails at the L1 point, keep on adding them until you've reduced the irradiation to your desired level.
Too much atmosphere? Throw rocks at it until you've blown enough away. Take care to not hit nearby occupied planets.
Genetically engineering carbon-fixing bacteria that can live at the cloud tops might be safer (for the nearby planets), and might well be easier.
For certain values of "hospitable" ... well ... yes.