Well for a start the gravitational field of Jupiter (for example) can change the path of a comet to collide with the planet. Additionally if the comet goes within the roche limit of a planet it can fall to bits. This causes momentum to be split between parts of the comet, resulting in much of the object entering the atmosphere. This was why we say shoemaker levy 9 on its last orbit. Looking further out the gravitational field of a planet can alter the orbits of comets so they have a resonant relationship with the planet. Resonance can lead to opportunities for collisions in the future.
My guess is that a comet orbits the sun dozens or hundreds of times before it hits anything, and many of them never come as close to the sun as the Earth anyway. When it does hit something the probability of an impact with a comet may scale with the mass of the planet. Jupiter has 317.8 time the mass of earth and 10 times the radius. Another guess is that the probability scales with cross sectional area (for the actual impact) and mass (for the effective range of the gravitational field). Multiply the two (because you need both to work together) and you get 317 * 10^2 = 31 000. Lets say one tenth of all comets which cross the orbit of Jupiter cross the orbit of the earth. thats another order of magnitude. So there should be 300 000 times as many impacts on Jupiter as on earth.
Don't quote me if we get hit. Comet insurance is your responsibility.
Another issue with the highly eccentric orbits is that a comet can do a close pass past the sun, and hit us almost directly from the direction of the sun. A large object on that trajectory could easily be missed entirely.
On earth we measure the intensity of UV light in Antarctica and conclude that the wrong sort of gas is being used in air conditioners in the tropics. Of course you have to follow a few steps from the observation to the conclusion, and uncertainty accumulates along the way. But thats science for you.
While we are at it, how can Toyota assemble an engine in a factory, sell it, and have it operate flawlessly for 20 years without even testing it once? I don't know either. Thats engineering for you.
So there's a mix here, but overall asteroids are more likely to strike without warning.
...until we catalog them. We can do that from low earth orbit with infrared telescopes. The wise mission has massively increased the rate of discovery, which is why I think the uncertainty about impacts will come from comets in the future.
We are rapidly learning more about the cometary impact rate on Jupiter, and now Neptune. It should be possible to extrapolate from this to calculate the impact rate on Earth.
Clearly, a dangerous object spends some time orbiting across the orbits of the planets before it hits something, and the probability of an impact on Jupiter is much greater than an impact on Earth.
We seem to be getting a handle on the risk from asteroids, but a comet can come our way without warning.
I don't either but my wife and my sister do. So if I need a message sent to my sister I ask my wife to do it for me. If she wasn't willing to do that I would probably need to register on facebook.
Also, one terminal on each side will get hydrogen. A different way would be to run a power ring around the Earth. Roughly: America to Europe to Asia to America and so on. Keep those electrons flowing. Areas with low demand sell power to areas with high demand.
I bought a pack of five phones a year ago and kept two for myself. One had serious audio problems while the other was very usable. As a phone this one is fine. For other, more modern stuff it is a bit limited.
2G networking is slow so web browsing is not really practical. The graphics are slow so applications which will work elsewhere won't work on this phone.
I run the SHR distribution which is built around Enlightenment. I wrote a bunch of applications for it which I have released as free software. I like the touch screen user interface, particularly for SMS.
I suspect the community is shrinking. I may move to Android in a year or so, or possibly a different linux based phone if I can have root access.
Makes me wonder if Europe+Africa could share power with North+South America. You could do it through the water. One conduction path in the south (Africa to South America) and another in the North (Europe to Canada). Maybe run DC through the water. Excess power on either side of the link could be offloaded to a different continent.
Both those boards get filled with spam, and some of the spam is advertising for child porn download services. In fact a lot of the spam is exactly that. The boards are moderated (sometimes) but the torrent of spam often gets ahead of the volunteer moderators. The landing page for 4chan and the other chans (7, 420, etc) advertise the boards they host. They target pop and counter-culture audiences. Its all very ad-hoc. Run on php scripts. There is no archiving or tracking of users. The low tech nature of the forums is one of the attractions for some people.
If the loop went in before the asphalt then it is probably deeper than one installed later on, so it will be less sensitive, as well as possibly being in the wrong location. In my years with our state road authority it was assumed that anything put down before the road was finished would be cut as a matter of principle, so we went in afterwards.
Here its a rectangle about 1500mm wide and 3000mm long. If you stop too far back it is very hard to miss the detector. A driver in a four wheel drive with raised suspension and overside wheels, who sitting ahead of the stop line revving their engine in anticipation of a green light and creeping forward will possibly never get that green light, unless somebody stops behind them to trigger it.
Just look for the loop cut into the road. As you say typically two or three car lengths back but you don't have to guess. Its a sawcut filled with polymer filler. Implementations I have seen will assume a queue exists if that loop is triggered for three seconds so stopping for a count of five should be enough.
This is how open street map build many of their maps, but its not automatic. If you are off the road you don't want the system to assume there is a road there.
There's got to be a better way to confirm the existence or non-existence of such must-avoid intersections.
Live traffic data I suppose. Traffic signals will calculate degree of saturation from dwell times on induction loop vehicle detectors. In most systems that data is passed up the chain to the software which does strategic traffic management. I have been out of the area for a while but I assume the live data is extracted at this point and aggregated into these live traffic data sets.
There aren't any asteroids 1/3rd the size of the Earth. The really big ones are in well understood orbits. All the impacts of that scale happened 4 billion years ago.
I reckon the vast majority of impacts will be similar to Tunguska, they will hit like a large nuke, but the effects will be survivable ~100km away, not a problem at ~1000km easy to miss at 10000km. The last impact like this was in 1908 and recent estimates suggest we might only get one every 1000 years.
Slashdot Mirror
Googling around 1.2.0 seems to have been for hardware released in 2009. Hard to believe that 1.1.4 came out before 2001.
Well for a start the gravitational field of Jupiter (for example) can change the path of a comet to collide with the planet. Additionally if the comet goes within the roche limit of a planet it can fall to bits. This causes momentum to be split between parts of the comet, resulting in much of the object entering the atmosphere. This was why we say shoemaker levy 9 on its last orbit. Looking further out the gravitational field of a planet can alter the orbits of comets so they have a resonant relationship with the planet. Resonance can lead to opportunities for collisions in the future.
My guess is that a comet orbits the sun dozens or hundreds of times before it hits anything, and many of them never come as close to the sun as the Earth anyway. When it does hit something the probability of an impact with a comet may scale with the mass of the planet. Jupiter has 317.8 time the mass of earth and 10 times the radius. Another guess is that the probability scales with cross sectional area (for the actual impact) and mass (for the effective range of the gravitational field). Multiply the two (because you need both to work together) and you get 317 * 10^2 = 31 000. Lets say one tenth of all comets which cross the orbit of Jupiter cross the orbit of the earth. thats another order of magnitude. So there should be 300 000 times as many impacts on Jupiter as on earth.
Don't quote me if we get hit. Comet insurance is your responsibility.
Another issue with the highly eccentric orbits is that a comet can do a close pass past the sun, and hit us almost directly from the direction of the sun. A large object on that trajectory could easily be missed entirely.
On earth we measure the intensity of UV light in Antarctica and conclude that the wrong sort of gas is being used in air conditioners in the tropics. Of course you have to follow a few steps from the observation to the conclusion, and uncertainty accumulates along the way. But thats science for you.
While we are at it, how can Toyota assemble an engine in a factory, sell it, and have it operate flawlessly for 20 years without even testing it once? I don't know either. Thats engineering for you.
So there's a mix here, but overall asteroids are more likely to strike without warning.
...until we catalog them. We can do that from low earth orbit with infrared telescopes. The wise mission has massively increased the rate of discovery, which is why I think the uncertainty about impacts will come from comets in the future.
We are rapidly learning more about the cometary impact rate on Jupiter, and now Neptune. It should be possible to extrapolate from this to calculate the impact rate on Earth.
Clearly, a dangerous object spends some time orbiting across the orbits of the planets before it hits something, and the probability of an impact on Jupiter is much greater than an impact on Earth.
We seem to be getting a handle on the risk from asteroids, but a comet can come our way without warning.
Email is so 2009. Haven't you heard?
I don't either but my wife and my sister do. So if I need a message sent to my sister I ask my wife to do it for me. If she wasn't willing to do that I would probably need to register on facebook.
Unidentified Flying Submarines?
Also, one terminal on each side will get hydrogen. A different way would be to run a power ring around the Earth. Roughly: America to Europe to Asia to America and so on. Keep those electrons flowing. Areas with low demand sell power to areas with high demand.
I bought a pack of five phones a year ago and kept two for myself. One had serious audio problems while the other was very usable. As a phone this one is fine. For other, more modern stuff it is a bit limited.
2G networking is slow so web browsing is not really practical. The graphics are slow so applications which will work elsewhere won't work on this phone.
I run the SHR distribution which is built around Enlightenment. I wrote a bunch of applications for it which I have released as free software. I like the touch screen user interface, particularly for SMS.
I suspect the community is shrinking. I may move to Android in a year or so, or possibly a different linux based phone if I can have root access.
Makes me wonder if Europe+Africa could share power with North+South America. You could do it through the water. One conduction path in the south (Africa to South America) and another in the North (Europe to Canada). Maybe run DC through the water. Excess power on either side of the link could be offloaded to a different continent.
"...would immediately hit /b/ within 30 minutes of them leaving work. "
I've seen a couple of references to this "/b/"....what is this?
NSFW links, but not as bad as people tend to make out.
http://boards.4chan.org/b/ The random board. A bunch of kids messing around basically.
http://boards.4chan.org/s/ A good source of porn.
Both those boards get filled with spam, and some of the spam is advertising for child porn download services. In fact a lot of the spam is exactly that. The boards are moderated (sometimes) but the torrent of spam often gets ahead of the volunteer moderators. The landing page for 4chan and the other chans (7, 420, etc) advertise the boards they host. They target pop and counter-culture audiences. Its all very ad-hoc. Run on php scripts. There is no archiving or tracking of users. The low tech nature of the forums is one of the attractions for some people.
If the loop went in before the asphalt then it is probably deeper than one installed later on, so it will be less sensitive, as well as possibly being in the wrong location. In my years with our state road authority it was assumed that anything put down before the road was finished would be cut as a matter of principle, so we went in afterwards.
What do we do if the target is Calcutta
If you're Pakistani you'd probably throw a party, not let the Indians in. "Yay! Nobody is aiming nukes at us any more!"
Unfortunately I think this scenario would almost guarantee the use of nukes.
Here its a rectangle about 1500mm wide and 3000mm long. If you stop too far back it is very hard to miss the detector. A driver in a four wheel drive with raised suspension and overside wheels, who sitting ahead of the stop line revving their engine in anticipation of a green light and creeping forward will possibly never get that green light, unless somebody stops behind them to trigger it.
Just look for the loop cut into the road. As you say typically two or three car lengths back but you don't have to guess. Its a sawcut filled with polymer filler. Implementations I have seen will assume a queue exists if that loop is triggered for three seconds so stopping for a count of five should be enough.
Open street map on my openmoko is very accurate.
This is how open street map build many of their maps, but its not automatic. If you are off the road you don't want the system to assume there is a road there.
There's got to be a better way to confirm the existence or non-existence of such must-avoid intersections.
Live traffic data I suppose. Traffic signals will calculate degree of saturation from dwell times on induction loop vehicle detectors. In most systems that data is passed up the chain to the software which does strategic traffic management. I have been out of the area for a while but I assume the live data is extracted at this point and aggregated into these live traffic data sets.
While we are on the subject: why have subject lines?
There aren't any asteroids 1/3rd the size of the Earth. The really big ones are in well understood orbits. All the impacts of that scale happened 4 billion years ago.
I reckon the vast majority of impacts will be similar to Tunguska, they will hit like a large nuke, but the effects will be survivable ~100km away, not a problem at ~1000km easy to miss at 10000km. The last impact like this was in 1908 and recent estimates suggest we might only get one every 1000 years.
Such a great book, and such a crap movie. Its a shame.