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Neon is more common than Nitrogen, which our atmosphere is chiefly composed of, yet none of the planets in our solar system have significant quantities of Neon in their atmosphere's.
Suppose a large terrestrial planet had an Earth-like atmosphere, but it's atmosphere was 78% Neon, with the remaining percentages being the same as Earth's.
Now, say we went to explore this planet, would we be able to breath in said atmosphere? And would the atmosphere look like Earth's or different?
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Depends on what the other components are...Originally Posted by Magnetar
Neon has the property that it is very weakly narcotic. Something like 3,5 times less narcotic than nitrogen.
This means that a man could safely breathe 10 atm neon provided that there is enough oxygen for breathing, not too much oxygen for oxygen poisoning, and not too much other poisonous gases, like nitrogen or argon in amounts to cause narcosis.
As for looks, there is Rayleigh scattering. How would the amount of Rayleigh scattering compare between nitrogen and neon?
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It might be difficult for an inner planet to have a lot of Neon in its atmosphere, since it has a low boiling point, and wouldn't tend to combine with any of the particles that create the planet.
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When I said:
I meant that I'm essentially taking an Earth atmosphere and replacing all the Nitrogen with Neon, the rest of the gases that make up Earth's atmosphere would be the same with the same percentages they have now.
Ok, thanks, that is helpful information.
I have no idea, hence me asking if the atmosphere would look the same.
So, the planet would need to be far away from it's sun so that the Neon wouldn't boil away. Could it be at a distance that the Neon could realistically exist while still not being too far out to be too cold for human inhabitants? Perhaps if the planet formed far out and then migrated inward?
Also I'm curious what the planets escape velocity would need to be in order to retain a thick Neon atmosphere.
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Jupiter seems to have considerably less Neon than it might have. From
http://en.wikipedia.org/wiki/Neon#Occurrence
But the helium content of Jupiter is not similarly depleted, so something odd is going on. It may be the case that gas giant planets in other systems do in fact have levels of neon content which are closer to the universal abundance. But a terrestrial planet would need to be significantly larger (or cooler) than the Earth to have a large neon component in its atmosphere. Someone with the right equations might be able to work out just how much bigger or cooler...Mass abundance in the universe is about 1 part in 750 and in the Sun and presumably in the proto-solar system nebula, about 1 part in 600. The Galileo spacecraft atmospheric entry probe found that even in the upper atmosphere of Jupiter, neon is reduced by about a factor of 10, to 1 part in 6,000 by mass. This may indicate that even the ice-planetesmals which brought neon into Jupiter from the outer solar system, formed in a region which was too warm for them to have kept their neon (abundances of heavier inert gases on Jupiter are several times that found in the Sun).
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If such an atmosphere do exist , with high content of neon , there must be some spectacular shows during storms. And as neon is relatively easy to ionize we may have a conducting atmosphere with very strange results. Many small lightnings instead of big one like on earth. And very red ! I am not sure but I think on Earth there is an electric potential in the atmosphere so imagine all the sky glowing faintly red !!! (Too much imagination)
Order of Kilopi
Neon has a lot of yellow and orange in it's line spectrum, too. Ought to make great thunder & lightning shows. As it's mass is ~ 20 Daltons...and nitrogen is ~ 28, it's density would have it drifting up in the atmosphere a bit, but not beyond earth's gravitational grip. The density gradient would cause a distinct change in voices, and other sounds as the speed of sound would be faster, like it is in helium. Deion Sanders should like it.pete
see, spectrum: http://images.google.com/imgres?imgu...%3Den%26sa%3DN
Last edited by trinitree88; 2009-Mar-29 at 05:47 PM.
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Another contribution to sound of speed would be the smaller heat capacity of neon, since it is monatomic.As it's mass is ~ 20 Daltons...and nitrogen is ~ 28, it's density would have it drifting up in the atmosphere a bit, but not beyond earth's gravitational grip. The density gradient would cause a distinct change in voices, and other sounds as the speed of sound would be faster, like it is in helium. Deion Sanders should like it.
Mind you, nitrogen might be dissociated into atoms by UV or collisions and escape the atmosphere in that form. Neon cannot.
Order of Kilopi
Not all sounds would be affected by a change in the speed of sound.
A resonant cavity (like the one responsible for picking out the dominant frequencies of the human voice) will change its characteristic resonant frequency if it is filled with a different gas mix, and so its pitch will change. But a vibrating string or tympanum will have the same resonant frequency, independent of the atmosphere; so our altered atmosphere will simply transmit the same frequency at a different speed of sound. The wavelength of the sound will therefore change, of course, but our ears respond to frequency, not wavelength.
Grant Hutchison
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Do you have a source for that claim?
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Ahh, I get it. Astronomers think of abundance about as often by number as by mass - neon atoms are just about 1.5 times as massive as nitrogen, so there are slightly more nitrogen atoms in a generic galactic mix as neon. This fits with the usual pattern H, He, O, C, N, and Ne coming in just afterward. (The abundances by number enter more directly into interpreting spectra, for example).
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That's the first I've heard of that. Maybe it's best not to broadcast this fact too openly, otherwise politicians might enact laws banning it!
As above, so below
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You might have missed his point. It's less narcotic than nitrogen. At elevated pressures (such as those involved during deep sea scuba diving) breathing ordinary air can result in nitrogen narcosis. Neon would have less of this tendency, although divers doing extended work at great depths might actually use helium mixtures.
Nick
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I was really just commenting on the reaction that some people might have to the word narcotic, in general, so didn't really mean anything about the neon/nitrogen comparison.
As above, so below
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C, O, and Ne are assembled (among other ways) by Helium 'burning'. They are the result of slamming alpha particles together. B, N, and F are a little harder to make in quantity, and the isotope/element abundances bear that out.
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As Grashtel says:
Prior to looking there though, I actually read about it in a book called World Building by Stephen Gillett, and then I looked it up on wikipedia which confirmed what was said in the book.
Interesting.
What if the atmospheric pressure was higher than it is on Earth? Would that make a difference in terms of how things sound in a Neon atmosphere?
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The speed of sound is pretty insensitive to atmospheric pressure.What if the atmospheric pressure was higher than it is on Earth? Would that make a difference in terms of how things sound in a Neon atmosphere?
What trinitree88 is talking about (I think) is a difference in density at some standard pressure. That's a surrogate for the mean molecular mass, which bears an inverse relationship to mean molecular velocity, which correlates with speed of sound. So one standard atmosphere of neon will have a lower mass, higher molecular velocity, and therefore higher speed of sound compared to one standard atmosphere of nitrogen. Compressing the neon (at constant temperature) doesn't change its molecular velocity, so doesn't alter the speed of sound.
Grant Hutchison
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I would like to see the auroral displays on a planet with a neon atmosphere (with the added proviso that I survive to tell the tale...)If such an atmosphere do exist , with high content of neon , there must be some spectacular shows during storms. And as neon is relatively easy to ionize we may have a conducting atmosphere with very strange results. Many small lightnings instead of big one like on earth. And very red ! I am not sure but I think on Earth there is an electric potential in the atmosphere so imagine all the sky glowing faintly red !!! (Too much imagination
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Yes, but since sound propagates adiabatically, speed of sound depends on heat capacity even for a given molecular velocity!
True.
But something that does depend on pressure is the acoustic impedance, and the contrast of acoustic impedance between air and flesh.
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Indeed, for the neon/nitrogen comparison, there's also a jigger factor arising from the difference in adiabatic index between monatomic and diatomic gases. That will increase the speed of sound over and above the effect of reducing the mean molecular mass.
Grant Hutchison
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I will attempt a summary, but first a rant. ~20 daltons, boo-hiss. Please, let's do what we can to slow the proliferation of units named after people. Did any of us decide on a career in science in hopes of getting a unit named after us? = Very little motivation, but the thousands of units that need to be learned to get an engineering degree is definitely a deterrent and makes most people think egotistical nerds. The MKS system unit for density is kilograms per cubic meter. An other approach is the atomic weight, which works well for true gas, especially noble gas such as neon = 20 and helium = 4. So neon has 5 times the density of helium under the same pressure and temperature. The squeaky voice should be barely noticeable breathing neon with the optimum amount of oxygen.
We think the planets start to form before the proto sun gets very hot, but my guess is ambient temperature on the protoplanet surface is above the boiling point of neon = -246 c, so the low boiling point likely has little effect. In some simulations the surface is 1000 c = 1832 f due to bombarding accretion. The "does not combine with other elements" does not seem to have hindered Earth having almost 1% argon. Neil
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And what are the units for those atomic weights you've just quoted?
Grant Hutchison
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...Except that the Argon we have here is a decay product of a fairly long-lived isotope of Potassium, and not something that got here as a noble gas originally.
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Lots of interesting info, thanks for all the input everyone, feel free to continue to chime in with any other thoughts you have.
And if anyone knows what the planets escape velocity would need to be in order to retain a thick Neon atmosphere, I'm still interested in that as well.
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That depends on the Temperature, but an Earth-sized planet at Earth's temperature, with a good magnetic field to protect it from solar wind, should be plenty.
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Not really...
How do you decide when a planet would retain a dense nitrogen atmosphere?
The energy of a molecule is proportional to temperature.
The solar constant is proportional to inverse square of distance to Sun. And black body radiation is proportional to fourth power of temperature. Therefore the temperature is proportional to inverse square root of distance to Sun, and so is energy of molecules.
Therefore the speed of molecules is proportional to inverse fourth root of distance to Sun.
Mars is roughly 6 times closer to Sun than Saturn. Therefore the nitrogen molecules in the atmosphere of Mars should be about 1,6 times faster than the molecules in the atmosphere of Titan.
Yet the escape speed of Mars is 1,9 times the escape speed of Titan.
Why then does Titan have a thick mass of nitrogen (1,6 bar) yet Mars has a very sparse nitrogen amount (200 microbars)?
Note that if a body is significantly smaller than Earth and less dense, with escape speed barely high enough to retain a massive neon atmosphere (like Titan), then the neon atmosphere would have large thickness for a given surface pressure (and therefore scatter a lot of light). Low gravity and dense atmosphere would also favour flying.
Order of Kilopi
Yes, neon seems to be heavy enough for the Earth to retain for geological timescales.
So I'm guess its rarity on Earth relates to its inertness and lightness relative to other chemical compounds that formed in the solar nebula: the Earth formed with very little neon, rather than losing it later.
Grant Hutchison
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It really does.Not really...
But of course it also depends on other things, too, as I'm sure antoniseb would agree.
Grant Hutchison
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Any thoughts on the atmospheric color? Would it be the same as with nitrogen or different?
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