Slashdot Mirror
Rings Around Earth From Ancient Meteorites
HorsePunchKid writes "According to an article on CNN (SNL version), ancient meteorites may have glanced off of the surface and shattered, causing rings around the Earth. These rings, which may have persisted for hundreds of thousands of years, could have had a profound effect on the climate in tropical regions, where the rings would block out light from the Sun. Still rather speculative, but the theory may help explain some patterns observed in the geological record. The idea has been around for a while, and some scientists are skeptical."
Look here.
Can't you see that everyone is buying station wagons?
Actually since the Big Bang occured in all parts of the universe at the same time, because the universe was an infinatly small point, the leftover radiation is everywhere in the universe. It hasn't traveled as much as the universe has increased in size.
Or I could be trying to do astronomy in my head right after I woke up.
Feminism is the radical notion that women are people.
Steven N. Severinghaus
Unless something acts on it near apogee to circularize its orbit, that orbit will return to the point it began (which lies inside the atmosphere)
No. The model of orbital mechanics that you are using does not contain enough objects. Here is a more realistic way of visualizing the process:
Instead of looking at one chunk of rock in a billiard-like model, think in terms of the spray of material that would be generated by a glancing strike (which is also the most likely kind). Most of the particles in this spray will not have orbital velocity and will rain back down, with the larger and faster ones making a string of secondary impact craters. A much smaller portion will reach escape velocity and become interplanetary objects.
But what is significant is the group of particles whose velocities exceed orbital velocity but do not reach escape velocity. That is a pretty wide range of speeds. At first these objects will also have a wide range of apogees and perigees, but they will mostly be in the same plane. Their own gravitational interactions and collisions will redistribute the kinetic energy of the group as a whole into a ring. In essence, the circularizing agent that you are looking for is the aggregate effect of the group on each individual member, a sort of gravitational peer pressure. Ring formation is probably a positive feedback process, where the proto ring's growth increases its influence on the remaining wild particles.
There are three ring shepherds that will cause any debris ring (any satellite for that matter) to seek an equatorial orbit over time: the Sun, the Moon, and the Earth's equatorial bulge. I imagine the Moon's presence would also assure that any Earth ring would be relatively short lived.
I would also think that any Earth ring formed in this way would be quite bright, at least for a while. I would think the ejecta stream would suck along a lot of air and water vapor through entrainment, and that many of the ring particles would be frosted as they cooled.
I'm not saying I'm convinced that this happened. But it is an intriguing scenario and might go far to explain ice ages and such. One of the more intriguing things about it is that it appears to be testable in several different ways.
What Dinosaurs? Excuse me, where are the Dinosaurs in the Bible? Well, which one is it, are we listening to the Bible or not?
Dinosuars are in the Bible.
They why do we see a steady rise in the level of atmospheric CO2 over the last 50 years, an increase that is about what we'd expect based on the amount of fossil fuel burning, etc? (Again, the Keeling curve). Natural CO2 releases may be larger, but if they are in equilibrium with CO2 sinks, even a small increase in net CO2 input can cause a steady rise in atmospheric CO2 levels. (At least until the sinks catch up, which takes time, and may not occur at all). Either way, we are seeing an increase, and isotopic signatures show that the carbon comes from fossil fuels (no C12).
Another way to make the point: look closely at the Keeling curve and you will see small variations that are in sync with the seasons. This is telling you that natural changes in CO2 respiration exist, are measurable, and are smaller than the large human-induced trend. In raw numbers, humans dump about 6Gt (gigatons of Carbon) per year into the atmosphere. The biosphere absorbs about half of that, the rest stays in the air.
I don't dispute that there could be some net heating. I DO dispute that it's significant
Well, there are several groups that have made estimates of the heating. As I recall it will likely be between 0.5 and 6 degrees (C) in the next century, with a peak in the probability function around 1-2. That is a larger increase than in other interglacial times, and it puts us in a climate regime that we haven't been in for at least a few million years (high CO2, warm. The typical situation has been colder with less CO2). We can argue a lot about detailed effects, but the climate will be different from now. There are a lot of models that suggest shifts in agriculture, and sea level rise. They may not be a problem for some rich guy in Colorado, but it will be a serious problem for Bangladesh (they have many). Of course, if you don't care about Bangladesh, fine. But keep releasing CO2 and in the next century it will be a problem for Florida.
No, you don't have to come up with a reason for the system to show natural warming .
If you accept that we are causing an increase in CO2, and you accept the physics of IR absorbption, my argument stands - why is the warming we see NOT due to the CO2 we release?
There have been very sudden movements in both directions in the past
For climate records such as ice cores it is often impossible to get good time resolution - so you can't tell the difference between an instantaneous rise and one that takes 2000 years. The rise in the past century is at least as rapid as any we have seen, and faster than most. Also, there may have been climate change, but nothing says it didn't have serious effects on life at the time. There have been large species die-offs related to climate change in the past. If anything, this reinfoces the point that it may be hazardous to jolt the climate severely. maybe not in terms of wiping out all life on the planet, but certainly in terms of causing e.g. agricultural disruption.
To pretend that those scientists that are promoting the theory of global warming have absolutely no financial interest in the results and are any more professional or ethical than those paid for by oil companies is very, very naive.
I don't know about that. There tends to be an extra layer of insulation between government-funded scientists (who by and large worry about global warming) and the financial interests. Certainly with the current U.S. administration there is no incentive for government scientists to exaggerate the seriousness of global warming.
The problem is that there are politicians out there advocating drastic changes in our social, political, and economic systems based on partial, in-progress results.
Actually, they seem to be advocating small changes in how we produce and consume energy, changes that will likely have to be made sooner or later anyway (we can't go on burning oil this inefficiently forever). In fact, dealing with global warming may well stimulate innovation and help the economy. After all, improving energy efficiency make the economy work better. The converse is certainly true - look at the former Soviet Union for an example of what can happen to a wasteful industrial economy.
Another problem is that the scientists themselves are telling us (the world AND the politicians) what we need to do. That's not science, that's politics.
Since when does the mere fact that someone is a scientist disqualify him or her from making policy recommendations? After all, in the U.S. every idiot is entitled to an opinion, logical or not. If someone who is intelligent and well-educated spends a lot of time studying a problem and comes to the conclusion that action is needed, why should we ignore that persons opinion? I know anti-intellectualism is alive and well in the states, but that doesn't make it wise.
Scientists are the "clergy" of the 21st century. When "scientists" start making policy we will again have a theocracy that the "separation of church and state" was supposed to protect us from. Just now the clergy will be made up of "scientists" rather than religious people. The political result is the same.
Now this is a lovely topic for a long discussion, but I have to get back to work. However, I will say this: there is a big difference between science and religion. Religion claims to have a monopoly on the truth, and hence once the Pope or the Mullah or clergy or whatever has spoken (as the mouthpiece of God, of course) there can be no argument. Science, when it works properly, is always ready to admit error. That makes it possible to improve science. Why does this matter? Well, it makes for a big difference in the political end result: a theocracy burns dissenters at the stake. A democracy with engaged scientists has a fruitful, ongoing debate. Also, with scientists involved in the debate you can actually get informed opinions. Otherwise it's just a big gab-fest ,i.e. slashdot.
Human genome = 3 billion base pairs = 6 GBit. Windows + Office = 20 Gbit. Which is more impressive?