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Coffee House => Coffee House Boards => CH / Science and Technology => Topic started by: blobrana on August 16, 2006, 01:22:17 PM
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According to the new draft definition, by the International Astronomical Union (IAU), two conditions must be satisfied for an object to be called a "planet." First, the object must be in orbit around a star, while not being itself a star. Second, the object must be large enough (or more technically correct, massive enough) for its own gravity to pull it into a nearly spherical shape. The shape of objects with mass above 5 x 10^20 kg and diameter greater than 800 km would normally be determined by self-gravity, but all borderline cases would have to be established by observation.
If the proposed Resolution is passed, there will be 12 planets in our Solar System; Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Charon and 2003 UB313 (aka Xena). The name 2003 UB313 is provisional, as a "real" name has not yet been assigned to this object. A decision and announcement of a new name are likely not to be made during the IAU General Assembly in Prague, but at a later time. The naming procedures depend on the outcome of the Resolution vote. There will most likely be more planets announced by the IAU in the future. Currently a dozen "candidate planets" are listed on IAU's "watchlist" which keeps changing as new objects are found and the physics of the existing candidates becomes better known.
The draft "Planet Definition" Resolution will be discussed and refined during the General Assembly and then it (plus four other Resolutions) will be presented for voting at the 2nd session of the GA 24 August between 14:00 and 17:30 CEST.
IAU blog (http://astronomy2006.blogspot.com/)
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yeah, I read this the other day. I guess Pluto will finally gets it's "wings' and no longer be an orphan. maybe we should celebrate! :cheers:
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I thought Charon was Pluto's satellite?
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It was. Maybe it was "upgraded" to a planet.
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Karlos wrote:
I thought Charon was Pluto's satellite?
maybe they had a falling out?
:-D
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I like this definition a lot. It's elegant, scientifically sound, and becomes only questionable in the case of small rocky objects which are by accident round or dense enough to become (nearly) spherical. It will take a while for me to call Ceres a planet (being used to the familiar chant Mercury-Venus-Earth-Mars-Jupiter-Saturn-Uranus-Neptune-Pluto), but I like it nonetheless.
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Cymric wrote:
being used to the familiar chant Mercury-Venus-Earth-Mars-Jupiter-Saturn-Uranus-Neptune-Pluto
I thought it was:
Mercury-Venus-Earth-Mars-Jupiter-Saturn-Uranus*snigger*-Neptune-Pluto
:-D
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Not if your native language is Dutch.
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Karlos wrote:
I thought Charon was Pluto's satellite?
If this proposal goes ahead, they will probably become binary planets.
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bloodline wrote:
Karlos wrote:
I thought Charon was Pluto's satellite?
If this proposal goes ahead, they will probably become binary planets.
Ok, so what about our moon? Not to mention those of the gas giants?
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Hum,
our moon (under the new rules) would sill be a moon, because the centre of its orbit lies within the Earth. This would be the same as the gas giants moons.
Pluto - Charon centre of gravity is in the space between them, so they become a binary/double planet.
My blog (http://www.activeboard.com/forum.spark?forumID=58381&p=3&topicID=7953593)
A relatively simple analysis show that there are currently 53 known objects in the solar system which are likely round. Another few hundred will likely be discovered in the relatively near future. Regardless of what the official count is from the IAU proposal these object all fit the scientific definition of the word planet and if the scientific definition is to have any credibility they should all generally be considered planets.
Mike Brown discoverer of the planet Xena has written a nice webpage (http://www.gps.caltech.edu/~mbrown/whatsaplanet/) that outlines a few points.
Incidentally, with the introduction of new planets we also have to also expand the zodiac. The planet Ceres this week is in the constellation Piscis Australis at about magnitude of 7.62 (at close approach).
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Mike Brown wants to have his cake and eat it too. He likes the science, but abhors the bureacracy which the definition would entail. Make up your mind, will you?
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blobrana wrote:
Hum,
our moon (under the new rules) would sill be a moon, because the centre of its orbit lies within the Earth. This would be the same as the gas giants moons.
Pluto - Charon centre of gravity is in the space between them, so they become a binary/double planet.
Ah, so the mass/size/dimension alone are not sufficient for planet labelling, it depends also on where the barycentre lies. Makes sense I suppose.
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Incidentally, with the introduction of new planets we also have to also expand the zodiac. The planet Ceres this week is in the constellation Piscis Australis at about magnitude of 7.62 (at close approach).
its all bollocks any way but wouldnt that mean that all the previous predictions were incorrect?
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nadoom wrote:
Incidentally, with the introduction of new planets we also have to also expand the zodiac. The planet Ceres this week is in the constellation Piscis Australis at about magnitude of 7.62 (at close approach).
its all bollocks any way but wouldnt that mean that all the previous predictions were incorrect?
They probably had to rejig it all anyway when pluto was discovered ;-)
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how cheated they must have all felt when pluto was discovered! :crazy:
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Hey you two! Don't mock others beliefs... Even if they are provably utter rubbish...
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@bloodline
:lol:
I was going to say it's too much fun, but yours is better!
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Vincent wrote:
@bloodline
:lol:
I was going to say it's too much fun, but yours is better!
:-D
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Video streams from XXVIth GA IAU Prague Congress Centre.
Weblink (http://www.astronomy2006.com/media-stream-archive.php)
The heated planet debate link is at the bottom.
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Wasn't there a couple of planets beyond Pluto called 'Smiley' and 'Cala'?
And what about planets that have been partially destroyed and no longer orbit a star... like Krypton!
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Woohoo!
Astronomers have approved the historic new planet definition guidelines (http://www.activeboard.com/forum.spark?forumID=58381&p=3&topicID=7953593&commentPage=2) today, and downsizing Earth's neighbourhood from nine principal heavenly bodies to eight by demoting Pluto.
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Oh Snap!! bye Bye Pluto!! :-o
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So they went for the first solution stated in mike brown's page. I think it's the most logical one for reasons explained in the page. a brave decision. will take some time to get used to though.
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demoting Pluto
NNNNNNOOOOOOOOOOOOO
say it isn't so. mickey will be so sad.
anyway seriously i kinda expected this but i had almost thought that we were going to end up with more planets out of this.
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countzero wrote:
will take some time to get used to though.
really?? it took me about 2 seconds.
Pluto is now a "dwarf planet"
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it said on the news they were adding planets not taking them away :(
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Good bye Pluto!
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I see the backlash (http://news.bbc.co.uk/1/hi/sci/tech/5283956.stm) has already started !!
my personal take:
Pluto is not a planet. its too small, there are other objects that arent automatically planets that are the same size, or bigger, such as 2003-UB313 'Xena' (what a crap name!)
I reckon on the Earth and Moon being a double planet - ok, it fails the barycentre test, but my opinion is based on the sheer size of our moon, and relative to the earth too. no where else has a moon this big in relation to the primary body.
There is a problem with the definition: 'must have cleared its orbital neighbourhood of other objects' this is done by either swallowing up these objects, or ejecting to another part of the solar system - this falls down when we consider that the earth, mars and indeed Jupiter have objects in their Trojan positions... ie: around the L4 and L5 Lagrange Points (http://en.wikipedia.org/wiki/Lagrange_point). does this now mean these 3 are not planets ?!
the battle rages on!!
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Agafaster wrote:
I reckon on the Earth and Moon being a double planet - ok, it fails the barycentre test, but my opinion is based on the sheer size of our moon, and relative to the earth too. no where else has a moon this big in relation to the primary body.
Charon (Pluto's moon) is significantly bigger in proportion to Pluto.
-Tig
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Vincent wrote:
Cymric wrote:
being used to the familiar chant Mercury-Venus-Earth-Mars-Jupiter-Saturn-Uranus-Neptune-Pluto
I thought it was:
Mercury-Venus-Earth-Mars-Jupiter-Saturn-Uranus*snigger*-Neptune-Pluto
:-D
Well since they got rid a planet, can't they rename "URANUS" to eleminate those tasteless jokes about the name.
something like .....
"Urectum" or "Uhemroid" instead :lol:
Uranus from Greek Mythology: The earliest supreme god, a personification of the sky, who was the son and consort of Gaea (Earth) and the father of the Cyclopes and Titans, who was castrated and dethroned by his youngest son, Cronus, at the instigation of Gaea.
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blobrana wrote:
Woohoo!
Astronomers have approved the historic new planet definition guidelines (http://www.activeboard.com/forum.spark?forumID=58381&p=3&topicID=7953593&commentPage=2) today, and downsizing Earth's neighbourhood from nine principal heavenly bodies to eight by demoting Pluto.
Pluto searching the "Help Wanted"!
Pluto Gets Downsized (http://www.hoolinet.com/CurrentEvents/PlutoGetsDownsized/tabid/312/Default.aspx)
:lol:
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Surely Pluto ought to be right at home in the planetory "Mickey Mouse" category :-)
*fetches coat*
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metalman wrote:
Well since they got rid a planet, can't they rename "URANUS" to eleminate those tasteless jokes about the name.
something like .....
"Urectum" or "Uhemroid" instead :lol:
Urectum was used in an episode of Futurama. The one with the garbage asteroid colliding with earth.
Great series that :lol:
@Karlos
Hmmm, starting to post some groaners again eh? ;-)
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Vincent wrote:
@Karlos
Hmmm, starting to post some groaners again eh? ;-)
Moi?
*blink*
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Agafaster wrote:
There is a problem with the definition: 'must have cleared its orbital neighbourhood of other objects' this is done by either swallowing up these objects, or ejecting to another part of the solar system - this falls down when we consider that the earth, mars and indeed Jupiter have objects in their Trojan positions... ie: around the L4 and L5 Lagrange Points (http://en.wikipedia.org/wiki/Lagrange_point). does this now mean these 3 are not planets ?!
Yeah, Jupiter's trojan clusters aren't exactly small either.
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Vincent wrote:
Urectum was used in an episode of Futurama. The one with the garbage asteroid colliding with earth.
Great series that :lol:
Missed that episode :-(
Agree, great series
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metalman wrote:
Missed that episode :-(
Shame, you've missed out on seeing Prof Farnsworths' Smelloscope...
*cue jokes about Uranus*
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metalman wrote:
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Well since they got rid a planet, can't they rename "URANUS" to eleminate those tasteless jokes about the name.
something like .....
"Urectum" or "Uhemroid" instead :lol:
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You're talking about Ur-Anus, aren't you?
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cecilia wrote:
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Pluto is now a "dwarf planet"
But isn't a "dwarf planet" still a planet?
So I'd say we now have 12 planets, with three of them beeing "dwarf planets"...
:-? :-? :-?
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Dandy wrote:
cecilia wrote:
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Pluto is now a "dwarf planet"
But isn't a "dwarf planet" still a planet?
So I'd say we now have 12 planets, with three of them beeing "dwarf planets"...
:-? :-? :-?
Actually we have four dwarf planets, though that number will grow significantly in the future. At present we have Ceres, Pluto, Charon and Xena, though Xena is not the actual name for the 4th dwarf planet, just a nickname, its actual name will be picked from a list submitted by its submitter next year sometime.
-Tig
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Dandy wrote:
cecilia wrote:
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Pluto is now a "dwarf planet"
But isn't a "dwarf planet" still a planet?
So I'd say we now have 12 planets, with three of them beeing "dwarf planets"...
:-? :-? :-?
no, a "dwarf planet" is a new designation (http://www.activeboard.com/forum.spark?forumID=58381&p=3&topicID=7953593&commentPage=2).
(2) A dwarf planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape2, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
It may be similar to a planet, but at least some scientists see a need for a more specific definition. I think there's going to be more discussion about it (we ARE talking about scientists, after all), but that's the way things stand now.
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Hum,
similar to `minor planets` (which now has been outlawed)...
i personally don't like the name `Dwarf planet` so i just use the terms `Asteroids` which is probably still OK, and `Kuiper belt objects` to describe the 200+ dwarf planets in the distant parts of our system.
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there's always "plutonian objects"
:-D
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blobrana wrote:
Hum,
similar to `minor planets` (which now has been outlawed)...
i personally don't like the name `Dwarf planet` so i just use the terms `Asteroids` which is probably still OK, and `Kuiper belt objects` to describe the 200+ dwarf planets in the distant parts of our system.
Possible definitions:
midget planets - small but spherically proportioned
dwarf planets - small and irregularly shaped
minor planets - infant or juvenile, not reached the age of consent
Or maybe not :lol:
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If they demote Uranus I'm going to get NASTY!
(http://www.youknowsit.co.uk/lowtech/mystic/Gamesmaster/gamesmaster.jpg)
by Tigger:
its actual name will be picked from a list submitted by its submitter next year sometime.
Woah... picked by the submitter of the submition... that's exactly what Tony Blair/Saddam Hussein would do!
Astronomy must be a fascist science!
Just out of curio... can you land a probe onto any of the gas giants or would it be crushed? How many of our planets could (wo/)man actually walk on (and would this include the asteroid planets?).
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Tigger wrote:
Agafaster wrote:
I reckon on the Earth and Moon being a double planet - ok, it fails the barycentre test, but my opinion is based on the sheer size of our moon, and relative to the earth too. no where else has a moon this big in relation to the primary body.
Charon (Pluto's moon) is significantly bigger in proportion to Pluto.
-Tig
True, but since Pluto isnt a planet, Charon isnt a moon (open floodgates!) - so The Moon is the largest moon in our solar system ;-) and in relation to its primary too!
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Our moon isn't as large as Ganymede, Callisto, Titan or Io, so it's far from being the largest.
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isnit ?
-checks wikipedia-
bloody hell! you're right, I sit corrected !
it is the 5th largest though, and I stand by the ratios thing, and the nitpicky that charon isnt really a moon.
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True, but since Pluto isnt a planet, Charon isnt a moon (open floodgates!)
Not necessarily true - "moon" seems to be used for any body which orbits a larger one (see http://en.wikipedia.org/wiki/Natural_satellite ).
On that note, I find it interesting that no one cares about how many moons we have - we have 240 known moons, some of them as small as 1km, and no one finds that strange...
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Perhaps I'm a bit late on this thread, but I thought that Pluto was no longer considered a planet? In fact, I have read that this has created some animosity in the astronomy community.
-Miked
/Edit Just read through all the responses.. helps to read them all before responding :-)
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Hyperspeed wrote:
Just out of curio... can you land a probe onto any of the gas giants or would it be crushed? How many of our planets could (wo/)man actually walk on (and would this include the asteroid planets?).
Current tech would have issues on most of the gas giants, high temperatures and in some cases very high radiation is likely not to allow landings there, though at least Wikipedia seems to imply that Venus has the highest pressue of the planets. Uranus would be the easiest to do it on, its been suggested we could mine Helium-3 there with a possible manned base on one of the moons. Man could walk on Mars, Mercury (temp on sunny side would be an issue), Venus (Atmospheric pressure about that same as being 3000 feet underwater, so you'd need good gear), plus all 4 Dwarf Planets and most of the moons, asteroids, etc.
-Tig
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Venus has the highest atmospheric pressure for any rocky planet. Atmospheric pressure is a somewhat vague concept when applied to gas giants such as Jupiter and Saturn as their atmospheres increase in density as you descend into them until you eventually end up in a layer where the pressure is so immense that the hydrogen has been crushed into a metallic phase. There's no distinct phase change boundary that represents any surface you could land on.
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Has man created a metallic hydrogen on Earth, sounds like good bomb material!
:-D
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I dare say its possible to take frozen hydrogen and compress the hell out of it in some very high pressure extrusion type systems (the sort that can fluidize cold steel) but I expect it would stop a long way short of making MH. The sort of pressure needed to make metallic hydrogen would surely have an adverse effect on whatever material you were trying to crush it with.
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If it could be created in a collider or something then surely this would be THE perfect anti-matter for long haul space travel!?
Another thing that has interested me lately is gravity. Can it be simulated by spinning an object around in circles as portrayed in the Bond film 'Moonraker' and do asteroids have sufficient gravity to be able to walk on them?
If gravity is linked to mass, then what proportion of our Earthly gravity is created by the crust, mantle and the dense metallic core? I read that some places in India you can weigh 1% lighter! When there is a 'full moon' how much counter-gravity is generated and would it save fuel to launch a rocket at a full moon (after all they save fuel by launching near the equator)?
:-D
EDIT:
Tigger (http://frogstar.soylentgeek.com/wav/onlyone.wav)
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Karlos wrote:
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Atmospheric pressure is a somewhat vague concept when applied to gas giants such as Jupiter and Saturn as their atmospheres increase in density as you descend into them until you eventually end up in a layer where the pressure is so immense that the hydrogen has been crushed into a metallic phase.
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Hum - IIRC hydrogene (under "normal" conditions pressure- and temperature-wise) is a gas, which becomes liquid at the "absolute zero" (-273°C) - no lower temperature is possible in this universe.
If you increase the pressure of an gas, the temperature will increase instead of lowering.
There are four conditions of aggregation:
1) gaseous
2) liquid
3) solid
4) plasmic
If you have an gas and you want to make it liquid, you have to cool it down far enough.
If you then want to make the liquid solid, you have to cool it down even further (e.g. steam-water-ice), which works for water and others, but not for hydrogen.
It just becomes liquid at the absolute zero point of temperature - so I would assume it to be impossible in this universe to have "solid hydrogen" or "frozen hydrogene"...
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cecilia wrote:
Dandy wrote:
cecilia wrote:
...
Pluto is now a "dwarf planet"
But isn't a "dwarf planet" still a planet?
So I'd say we now have 12 planets, with three of them beeing "dwarf planets"...
:-? :-? :-?
no, a "dwarf planet" is a new designation (http://www.activeboard.com/forum.spark?forumID=58381&p=3&topicID=7953593&commentPage=2).
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Hum - a giant planet still is a planet.
So a "dwarf planet" still is a planet as well, I'd say - just smaller and maybe not so perfectly spherically shaped - but nevertheless still a planet (at least for me)...
Otherwise they would have dropped the word "planet" from the name, wouldn't they?
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Hum,
it is perhaps better to say `Kuiper-belt object` instead.
BTW, The KBO that was nicknamed Xena, and it's moon Gabrielle have now been officially designated the names Eris and Dysnomia.
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@Dandy
I studied chemistry to postgraduate level so phase diagrams are no stranger :-)
I think you are thinking of Helium. Hydrogen's melting point is at 14K and the solid phase is well characterised. Helium, under 1 atmosphere pressure is still liquid as close as anybody has ever gotten to absolute zero (a temperature which is basically impossible to achieve in reality). Helium will solidify under 1.5K if you subject it to at least 26 atmospheres. Below about 4K at normal pressure, Helium (at least He4) switches to it's superfluid phase, which is a highly interesting state where the viscosity of the liquid effectively vanishes and the thermal conductivity becomes immense. It'll creep over any surface and find it's own level within any enclosed space, regardless of the topology. The thermal conductivity means you can't boil it, for example, the heat is dispersed so quickly through it that it simply evaporates to a gas phase.
Crazy stuff.
Going back to hydrogen, under enough pressure and temperature it becomes metallic (http://en.wikipedia.org/wiki/Metallic_hydrogen), and may even be superconducting.
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Would Hydrogen retain it's metallic form after the conversion process? Could we all be wearing hydrogen rings in the future that could power our house?
:-D
I saw liquid Helium on Sky TV years ago, if you take the lid off the container it screams like a falling bomb and tries to do a runner!
In my opinion to be a planet the object must be perfectly spherical. A designation would be mathematical. Can non-spherical objects retain an atmosphere?
Interesting is the fictional 'world' of Halo... a weapon/planet who's entire surface is the inner track of a giant ring. Maybe we should start thinking of more designations when technology allows us to make our own worlds or discover things that don't fit the mould!
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Hyperspeed wrote:
Interesting is the fictional 'world' of Halo... a weapon/planet who's entire surface is the inner track of a giant ring. Maybe we should start thinking of more designations when technology allows us to make our own worlds or discover things that don't fit the mould!
Thats a steal from Niven's Ringworld, which is a sub idea of Freeman Dyson's shell or as its more commonly known today, a Dyson Sphere.
-Tig
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Karlos wrote:
@Dandy
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I think you are thinking of Helium. Hydrogen's melting point is at 14K and the solid phase is well characterised.
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No, no - I was thinking of hydrogen.
I thought I was taught that the boiling point of hydrogen is at 0 K.
But now that I read about hydrogen at wicki, I was rather astonished to read that the boiling point was not at 0 K, but at 20,4 K (= -252,8 °C) and that there even is a melting point at 14,025 K (-259,125 °C).
Hmmmmm - eigther I mixed it up after all those years or my teachers tought me BS...
But nevertheless:
(Quote from wicki)
"Many Experiments are continuing in the production of metallic hydrogen in laboratory conditions. Arthur Ruoff and Chandrabhas Narayana from Cornell University in 1998, and later Paul Loubeyre and René LeToullec from Commissariat à l'Énergie Atomique, France in 2002, have shown that at pressures close to those at the center of the Earth (3.2 to 3.4 million atmospheres), and temperatures of 100 K–300 K, hydrogen is still not an alkali metal. The quest to see metallic hydrogen in the laboratory continues, well beyond 70 years after its existence was predicted."
So I assume that all this talk about metallic hydrogen is just theoretical/hypothtical?
Karlos wrote:
Crazy stuff.
Indeed...
Karlos wrote:
Going back to hydrogen, under enough pressure and temperature it becomes metallic (http://en.wikipedia.org/wiki/Metallic_hydrogen), and may even be superconducting.
Yes, in theorie - as I understood it, up to now no one successfully produced metallic hydrogene...
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@Dandy
As far as I understood, they did make it, over the duration of the compression experiment (250ns).
Putting it in a jar, however is an entirely different proposition. The pressure required to keep it metallic is far beyond current material sciences' ability to produce a container for.
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Arthur C Clarke predicts that the core of Jupiter could be an enourmous diamond - a piece of this is found on the now melting moon Europa, in his books 2010/2061.
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Arthur C Clarke - a diamond geezer!
On this subject though how will world economics evolve over the next few centuries when asteroids, moons and planets are discovered with gold, uranium, diamonds etc. on them?
The UK had to sell off a lot of it's gold reserves a few years ago due to the falling prices... imagine the impact on a country's economy if it's reserves of some mineral were superseded by a mine on the moon!
I read a year or two back that a few scientists think that viruses come from space... that millions of tonnes of organisms live high up in the atmosphere and that they suggested viruses were literally raining down from the sky. Freaky.
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I don't expect a large diamond to exist in jupiter's core. A very large mass of heavily compressed iron, surrounded by a rock mantle up to several earth radii, then atmosphere all the way out, proceeding from metallic hydrogen (sustaining immense electric currents that power the magnetosphere) through a normal liquid phase and eventually gaseous, without any well defined boundaries between each.
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Do diamonds have electrical properties, like Quartz oscillates a current?
Such a perfect lattice should be capable of something extraordinary besides being very hard and twinkly!
:-D
I saw an astronomy program once where it described billions of volts arcing from Jupiter to one of it's moons, constantly. They also say that Jupiter is effectively Earth's guardian angel - absorbing all the asteroids.
What I have been thinking lately is that for planets like Neptune to orbit the Sun there must be some physical thing grabbing hold of them and keeping them in this ring of motion.
Now I've never studied physics academically but surely gravity must be a form of matter to have an effect on anything?
I couldn't make head nor tail of Steven Hawkings' nut book but I don't agree that time is interwoven with gravity. I believe the vacuum of space is in fact a solid entity filled completely with quantum particles and that the planets behave exactly like electrons around a nucleus.
Can anyone educate me or even propose wackier ideas?
EDIT:
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)?
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?
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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?
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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.
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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?
by Karlos:
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.
I'm sure the idea was to create an accelerated form of global warming on Mars. Why this was suggested I don't know - especially if the ice caps are CO². If the planet got warmer would any plants be able to live on CO² alone (they breathe oxygen during the night don't they?).
Imagine a plant that would breathe only CO² and emit oxygen, you could plant your own atmosphere generators! Hey, maybe even microbes could be engineered to survive the martian environment and generate oxygen or fuel.
With the nukes I didn't mean nuking our own ice caps. I did see some satellite style device on TV once that generated ozone but the estimated time of repair would have been 10,000 years with this basic gizmo.
This new idea of storing carbon dioxide underground though is a really bad one. One earthquake and you could release years worth of CO².
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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?
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Karlos: That was an excellent response - my mind is nourished.
:-D
Makes you appreciate how delicate our planet's life support system is.
With the ozone layer though, don't they say that farting cows are mostly to blame? And paddy fields... there's a lot of them in the far east.
You don't think like Aurora Borealis/Australis that the Earth's magnetic field and solar radiation has anything to do with the holes? Why are the holes... at the poles!?
;-)
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Vincent wrote:
Cymric wrote:
being used to the familiar chant Mercury-Venus-Earth-Mars-Jupiter-Saturn-Uranus-Neptune-Pluto
I thought it was:
Mercury-Venus-Earth-Mars-Jupiter-Saturn-Uranus*snigger*-Neptune-Pluto
:-D
I was alway taught that it was 9 planets at school. It will always be 9 planets! :-P
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get with the times, buddy.
it's 8 planets! :roll:
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cecilia: I'm afraid it's 9 planets (http://www.digital-audio.net/_aude/animan/yakkos_universe.mp3) and that includes Uranus and Pluto! (http://www.digital-audio.net/_aude/animan/uranus.mp3).
Hear blobrana try to explain away the mistake... (http://wbtower.ashyre.com/sound/clips/dot-cant_help.wav)
Left click the links ·IBrowse users·!
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@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.
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Karlos wrote:
@Hyperspeed
...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.
...
Could the polarity of the magnetic field play a role here?
I know you can separate bulk goods by leading them through an electro-static field - one component is attracted by the positive side and the other one by the negative side.
And after having read Einstein and Steven Hawking, I know that electric fields and gravitational fields are not *that* different...
:-?
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"These days it's been harder and harder to tan, ever since we lost the Ozone layer... but now I use Sunblock 5000 - see you by the pool!"
(http://www.robocoparchive.com/board/shop/images/sunblock5000.gif)
:-D
Wouldn't it be amazing if, in the future, we could dump a sort of counter catalyst chemical from space into the atmosphere and effectively rebuild the ozone layer. We could even have solar powered airships continuously replenishing the ozone or indeed microbes to do it...