Invisible/Translucent Planet

[heyo]

Some of the other threads, like the really cool one about the water-drop planet, has got me thinking.<br /><br />For example, Neptune is blue because of methane, but Hydrogen and Helium are mostly invisible (transparent if you will)<br /><br />I wonder if enough pure hydrogen and/or helium coalesced into a gas giant type planet, but was almost invisible, or semi translicent. Maybe it would just look like a hazy ball with no discernable edges, or maybe the pressure is high enough inside that the gasses will glow and there will be a glowing core inside a translucent ball of gas.<br /><br />What do ya'll think?<br /><br />Heyo

 

[vladius]

well, firstly it would be very detectable. That much mass would have a definite gravitational effect that would easily be detectable if it was in our solar system. like jupiter it would probably also have a magnetic field. if it were dense enough to stay together, it would have at least a liquid hydrogen/helium core. if it were difuse enough to be translucent, or transparent, it would simply be a hydrogen cloud, and not a planet at all. to be a planet, it would need quite a bit of mass, in order to keep the gas atmosphere. so... a transparent jupiter.. not possible.. now.. a water droplet planet... thast neat to think about. not sure if its possible.. but neat

 

[peacekeeper]

I don't quite get your point, Vladius. Why wouldn't it be possible? Sure, it would obviously have to be dense enough for gravity to hold togeather, but why would that make it liquid? Don't get me wrong, even I understand that it cannot be transparent all the way through, that it somewhere in the middle has to have a hot glowing core. But couldn't that core just as well be gaseous? Or would the preasure prevent that? Either way, I see no problem with at least half the diameter of the gas giant to be translucent.

 

[vladius]

Okay reasons why it cant be transparent<br /><br />1) (i only need one) for the same reason a glass of water is clear, and an ocean is blue. Hydrogen is not clear. niether is helium. If a planet was pure hydrogen (especially something as large and dense as a gas giant, or 1/2 gas giant) right to the core, it would absorb some parts of the spectrum, and reflect only a very few. Thats the basis of spectroscopy. now if the planet was as small as earth and was gas all the way through.. it would not be dense enough to be considered a planet, and may very well be quite clear... but still.. it would only be a cloud of hydrogen, and would probably disipate because of the lack of enough gravity to pull it all together. <br /><br />am i making sense?

 

[silylene old]

Assuming total transparency (not, but another subject), light passing through the hydrogen ball and would still be refracted. Hence the planet would be easily observed. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[thalion]

If the atmosphere were completely transparent, then the planet would still be blue due to Rayleigh scattering--no clear planets, unfortunately.

 

[najab]

><i>So while solutions consistent with physics can be created, they cannot be tested. So all solutions remain hypotheses, and their worth is related to how well they have been tested. In other words, the null set.</i><p>Huh?</p>

 

[vladius]

i agree with NajaB.. hey.. that rhymes.... <br /><br />The point is, it doesnt have to be tested. Physics says its not possible. to have a translucent/transparent planet. The only way... the only way where an Amosphere can be translucent/transparent is: if the planet had a dense solid core, much like earth, and there was no water/moisture on the planet to make clouds. Earths atmosphere would be transparent if there was no clouds. But if there was no core, there would be no atmosphere because there isnt enough gravity to coalece into a planet. plus our atmoshere is what? 60 miles thick (like looking at the glass of water in my other post)? Thats why gas giants have to be as big as jupiter/neptune/uranus.. they need ALL that mass of ALL that gas to give it the gravity to keep it all together into a planet (like the ocean in my other post). Now, granted, you dont need a planet as big as jupiter. maybe half the size of jupiter, or a little less. But even then, The pressure of all that gas, held together by gravity would give the planet a liquid hydrogen core. Just like propane. Propane is a liquid when its in the tank because the pressure doesnt allow it to evaprate into gas. but when its burned in your bbq, its in a gaseous state. If you had a planet 1/2 jupiter, there still would be too much mass to make it translucent. it would be compressed and dense because of the gravity, and hence when looking at it, and you would be able to SEE the hydrogen. Remember.. there is no such thing as an invisible atom. you put that much of anythign into that much of space, and youll be able to see it. hydrogen and helium are no exception. it would reflect light just as if it where any other planet. but depending on the gas make-up, you might get some exciting looking colors... just look at jupiter saturn, and neptune. preeettyy....

 

[nexium]

Hi VLADIUS: You should not say "not possible" The core does not have to be solid, nor dense. It can be very hot plasma. Improbable, I agree.<br /> You don't need much gravity or mass to hold it together, if external gravity and radiation fields are extremely weak. I think I agree transparency decreases with density and distance, so anything I can imagine approaches opac after 10,000 miles or so. Neil

 

[yurkin]

But it can be tested…<br /><br />The Raleigh scattering of a given amount of hydrogen under a given pressure can be tested in the lab. It can be tested at different densities to model the effect at varying depths.<br />Then it’s just a simply matter of integrating to find the total scattering from the entire hypothetic planet.<br /><br />We are very fortunate to live in a universe where the laws are the same in a planet and in a laboratory.<br />

 

[jatslo]

I think you’re on to something that none of these textbook huggers can fathom; however, something more massive than a planet might be required.

 

[jatslo]

<font color="orange">How could it be tested? By collecting several earth masses of hydrogen and see?</font><br /><br /><font color="yellow">That's not possible. So while solutions consistent with physics can be created, they cannot be tested. So all solutions remain hypotheses, and their worth is related to how well they have been tested. In other words, the null set.</font><br /><br />stevehw33, <br /><br />Your response is loaded CRAP!!!!!!<br /><br />They are working on the matter here:<br /><br />http://www.llnl.gov/str/Nellis.html<br /><br />And other places too!!!!

 

[Saiph]

One reason material is in the text books, is because it's very, very solid and investigated material.<br /><br />the reason you can't have an invisible planet is, under those pressures, it isn't a gas anymore. And if it isn't a gas, the types of light it can absorb broadens, the light passing through will hit something, and be blocked by atomic nuclei and free electrons (also bound to happen near the core).<br /><br />heck, if you had a pure hydrogen jupiter, you'd get, get this jatslo, metallic hydrogen near the core...which definetely has free electrons for absorbtion and scattering of photons. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[Saiph]

btw, try to find that outlined explicitly in a text book.<br /><br />The only thing you'll find is: Free electrons can scatter light. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[nexium]

If water is 30 meters deep, very little sunlight reaches the bottom. This is partly due to impurities, but a large thickness of all transparent materials is essentually opac. This also true of gases under high pressure and the pressure gets very high near the center of even moon size planets of gas or licquid. Likely all bodies are warm inside, if not hot. Neil

 

[rogers_buck]

It would actually be an interesting scenario if it were a star as well. When you look at an image of the sun, what you are seeing is the black body radiation emitted from the surface of the sun. The heavier elements (especially the metals) with their myriad of absorption lines render our sun opaque. <br /><br />A first generation sun made of nearly pure hydrogen wouldn't have the metals and would be largely transparent to a far greater optical depth. I think it would be quite beautiful.