How many planets?

[Karlos]

Trust me, if you believe in quantum mechanics at all, electron 'orbits' within atoms are about as different from planetary orbits as it is possible to get ;-) You simply cant apply macroscopic scale physics to the microscopic (as in atom scale) world, it simply breaks. It has been said that macroscopic physics is an approximation of quantum mechanics for where the 'uncertainty' limit is zero, rather than [d]h[/d]/2PI...

There's no real mystery about planetary orbts. Gravity is holding neptune in orbit. The sun's gravitational influence extends a hell of a lot further than that, too. Gravity as 'matter' is an explored idea, do a search for 'graviton' particles.

Regarding diamond, it's a very poor conductor. However, if you dope it with boron, nitrogen or similar atoms you can make semiconductors from it. Diamond has very good thermal conductivity, making it a very good future substrate, though it's expensive to make at the moment.

Having said that, carbon under billions of atmospheres of pressure and at tens of thousands of degrees kelvin, who knows what properties it would have?

[Karlos]

Hyperspeed wrote:

And while I'm off on a tangent here - can anyone explain if our moon, if artificially provided with one, could retain a very thin atmosphere (enough for humans to be able to breathe)?

No. First of all, RMS speed of gaseous nitrogen/oxygen molecules at standard temperatures are above the moon's escape velocity. Secondly theres' no decent magnetic field around the moon which means it takes the full brunt of the solar wind which would rapidly strip away any atmosphere it managed to keep hold of.

It was suggested that atom bombs could be used to melt the ice on Mars to speedily provide the planet with an atmosphere - how long would artificial atmosphere generation take using today's technology and could it be applied to Ozone regeneration on our own planet?

No. The idea on mars is to release the frozen CO2 in the caps, thickening the atmosphere, which is mostly CO2. As much as 1/3 of the atmosphere freezes out into the caps during Mars' winter.

Dropping nukes all over our ice caps would do nothing but make our planet even more screwed up than we managed so far. I suspect if it had any effect on ozone at all, it would deplete it.

[Karlos]

Hyperspeed wrote:

by Karlos:
No. First of all, RMS speed of gaseous nitrogen/oxygen molecules at standard temperatures are above the moon's escape velocity. Secondly theres' no decent magnetic field around the moon which means it takes the full brunt of the solar wind which would rapidly strip away any atmosphere it managed to keep hold of.

I see...but why do some moons have atmospheres? Doesn't Titan have one, or is this because it's big enough to hold one down?

The hint was in the word 'temperature'. Gas molecules statistically start to move faster as the temperature rises.  If you look up the Kinetic Theory of Gases, you will see a proof for

v(rms) = sqrt(3kT / M)

where v is the RMS speed of the gas molecules, T is the temperature in Kelvin, M the molecular mass of the molecule and k is Boltzmans Constant.

Two things you will observe about Titan (which has a dense atmopshere) and Triton (which has some atmosphere) is that they are both very, very cold. So much so that the bulk of the gases in their atmospheres are safely below their gravitational escape velocity. They are also quite large (Titan especially) but they aren't that dense so their gravitational pull is not as strong as their size might imply.

The second thing about these moons is that they are also sufficiently far from the sun to receive a much reduced solar wind flux, although theres still enough to erode an atmosphere as loosely held as they are. However, these moons are protected to a degree by their parent planet's magnetospheres. Even then, Titan bleeds gases into orbit around Saturn, though I recall there was evidence to suggest the lost gases are recaptured as they don't escape Saturn orbit and are within the protection of the magnetosphere.

Regarding Ozone, the stuff will naturally break down in darkness. You actually need UV light dissociating normal molecular oxygen to produce ozone ;-)

One thing about the hole in the ozone layer that always puzzled me. Most of the human population (therefore the CFC production with it) live in the northern hemisphere, yet the largest hole is in the southern one. At the altitudes involved, I don't envisage you'd get a large crossover (I could be wrong about that, however), so why isn't the larger hole in the northern one?

[Karlos]

@Hyperspeed

Well, regardless of the polar holes, the ozone layer is definately thinning globally if you look at the entire set of available data.

The evidence for CFC damage is pretty damning. The problem is that CFCs are extremely stable in the lower atmosphere, once released they will survive for a long long time. One 'debunking' argument is that they are denser than atmospheric gases and therefore wouldn't find their way up as high as the ozone. This is, of course, utter bilge. The atmosphere is not generally "sorted" by molecular weight, natural turbulence and diffusion are more than enough to get them up into the stratosphere.

Once they get there, the UV and particle radiation is enough to break the bonds between the carbon and chlorine atoms. This is where the problem starts. The chlorine atom released breaks down ozone *catalytically*. Therefore, one chlorine atom can break down any number of ozone molecules it comes into contact with. In other words, it only takes a small amount of CFC to reach the ozone layer, be decomposed to do a lot of damage.

There are natural sources of ozone depleting chlorine, such as volcanos etc, however they generally belch out hydrogen chloride (rather than chlorocarbons), which usually end up in clouds and getting rained back to earth. Also, hydrogen chloride doesnt exactly dissociate as readily, nor in the same way as a chloro carbon bond (you are much more likely to see H+ / Cl- than H / Cl).

I suspect the holes at the poles would be at least partially the result of their extended periods in the dark, during which time the ozone would decompose back to molecular oxygen. Perhaps some fluid dynamic behaviour of the atmosphere concentrates ozone depleting pollutants close to the poles, frankly I have no idea, but again if that is the case, I'd expect a larger depletion in the northern hemisphere, were most of CFC producing people live.

Methane and other gases would probably be oxidised by ozone in the presence of strong UV (thereby depleting it) but this reaction would not be catalytic - the methane would be converted to compounds that would, eventually, not be capable of further reacting with more ozone. This is quite a contrast to your chlorocarbon case where the liberated chlorine atom can destroy as many ozone molecules as it can come into contact with before eventually being lost from the atmosphere or captured in some other way.