Uranus’ atmosphere – creative help

[GoodUniverse]

I have a very strange question/request/hypothetical situation, whose answers will help me research a piece of artwork that I will be creating.

Imagine ascending through the clouds of Uranus in space craft, emerging atop puffy methane clouds. As you float higher in the atmosphere you encounter thin hazy layer of smog. Just then you look back towards the sun breaking over the horizon…

what colours do you see? Cyan clouds below from within a reddish haze? An Ice Halo breaking over the horizon? Thunder/Lightning below? Is it snowing Methane ice crystals? Are the winds blowing strongly?

What do you suppose? I am trying to create a scene of looking back towards the sun just breaking over the horizon from within the upper atmosphere.

Any input would be appreciated, thanks
Christian.

 

[GoodUniverse]

OK, perhaps I should provide a starting point. See below and list any issues you may have of the attached scene.. This is a view high up in Uranus' atmosphere looking back the Sun.
[PLAIN]http://www.gooduniverse.ca/blog1/wp-content/uploads/2010/12/gu_uranus_550.jpg

 

[armolinasf]

I just want to say that I've always kind of admired art like this in the same way I admire and enjoy science fiction, it gives you a window as to what's out there I guess.

As for the accuracy, you got the rings right: they are very thin and they would scatter light forward. Uranus does have numerous moons which keep those rings in place so you may want to include that.

One thing that does separate Uranus from the other giant's is that it has relatively little atmospheric activity, so there won't be too many giant storms.

Hope this helps a bit.

 

[qraal]

OK, perhaps I should provide a starting point. See below and list any issues you may have of the attached scene.. This is a view high up in Uranus' atmosphere looking back the Sun.
[PLAIN]http://www.gooduniverse.ca/blog1/wp-content/uploads/2010/12/gu_uranus_550.jpg[/QUOTE]

The clouds will be white - water, ammonia and methane all make white clouds. The colourations seen in the Gas Giants are from trace compounds probably involving sulfur and phosphorus. The atmospheres are very deep in the outer gas giants and the condensation level for the clouds is very deep down. At the one bar level (earth's sea-level) Uranus is still too cold for cumulus clouds from convection currents. Icy cirrus clouds are more likely, while the larger convection driven clouds will be deep down. The sky should be blue because the gas is still mostly hydrogen/helium. No weird greens or similar artistic tropes because stuff like ammonia is at trace levels in such cold.

 

[GoodUniverse]

Thanks qraal, this is most helpful.
Also, I have found in my reading that there is evidence of a hydrocarbon smog layer high in the atmosphere... I guess similar to smog on earth. Can I assume then if the sun were cutting through this layer that an orangey sunset might be possible?

 

[qraal]

Thanks qraal, this is most helpful.
Also, I have found in my reading that there is evidence of a hydrocarbon smog layer high in the atmosphere... I guess similar to smog on earth. Can I assume then if the sun were cutting through this layer that an orangey sunset might be possible?

I guess. Can't be very thick because it would be more strongly in evidence otherwise. Sunrise in the deep atmosphere would produce some pretty weird lighting with the light passing through so much atmosphere. Assuming light gets through. Go deep enough and it'd all be scattered into a directionless glow, like the bottom of Venus's atmosphere.

 

[GoodUniverse]

Well, I've changed it dramatically due to all the new information. This scene has the POV of just over the Troposhere looking down upon the layered clouds. Above are the thin wispy layers of smog and other gases and the nitrogen in the stratosphere is colouring it blue. Of course the Sun sitting low in amongst all the layers giving a colourful sunset effect.

[PLAIN]http://www.gooduniverse.ca/blog1/wp-content/uploads/2011/01/sunsets_clouds5_web.jpg

 

[GoodUniverse]

I was wondering if anyone would corroborate the existence of a yellow/orange sunset high in the atmoshpere of Uranus, if you were situated above the methane clouds looking at the horizon?

My reason for thinking so is because of the abundance of Hydrogen in the upper atmosphere and the fact the Rayleigh Scattering produces these effects on earth. Add to that thin cloud layers of hydrocarbons that are found there and I think you might have a beautiful sunset to look at.

Could this be true?

Christian.

 

[Sankaku]

I have no useful information for you. Just wanted to say I enjoyed your pictures!

 

[qraal]

Hi Christian

It's possible. The path length of sunlight traveling through the atmosphere is huge compared to Earth, so the scattering and refraction will do some pretty things with the light.

 

[GoodUniverse]

Thanks Sankaku, I appreciate your sentiment just the same.

 

[GoodUniverse]

Qraal, I am thinking so too. I am not a atmospheric specialist but the necessary elements seem to hint that it would be possible. The only thing I haven't considered here is that the strength of the Sun is 1/400 that of what we seen on Earth so this image will have to be darkened dramatically.

 

[GoodUniverse]

An intuition is as good a starting point as any I guess.

 

[GoodUniverse]

OK, here's my new one. I read somewhere that the rings are continuously shedding material down into the atmosphere, so I put a little meteor in for good measure. Enjoy.
[PLAIN]http://www.gooduniverse.ca/blog1/wp-content/uploads/2011/01/Uranus_v6_web.jpg

 

[Hurkyl]

The perspective of the rings is off. Remember that the rings are more or less a circle around the center of the planet -- a point that is more or less straight down all of your pictures. All of the arcs you've drawn look like they're centered on a point far to the side.

Maybe it's a minor point that won't bother people, but it was enough to make me instantly think something was weird about them, even though it took me a couple minutes to figure out what.


Unfortunately, I'm having trouble visualizing how they should look.

 

[GoodUniverse]

Hi Hurkyl,

If I have read your comment correctly, you are assuming the point of view is set on the equator. If you were off the equator, closer to one of the poles, you would see more of the rings' plane than just a narrow band directly above you.

 

[GoodUniverse]

Hurkyl, I should mentioned as well that Uranus does have seasons, as its ring system always stays pointed in the same direction during orbit around the sun. See illustration below

 

[Hurkyl]

Hi Hurkyl,

If I have read your comment correctly, you are assuming the point of view is set on the equator. If you were off the equator, closer to one of the poles, you would see more of the rings' plane than just a narrow band directly above you.

If you were at the poles, you would see the rings mostly parallel to the horizon, rather than mostly perpendicular. If you were standing on the pole, then the rings would appear at a constant height in the sky in all directions. (assuming they are actually above the horizon -- I have no idea if they are far enough from the planet to be seen from the poles)

But no matter where you are, the rings should appear as an ellipse whose center is the center of the planet. In any picture where the horizon is horizontal, the center of the planet is straight down. (Or straight up, I suppose)

 

[GoodUniverse]

The point of view I have created here is about 10-20 degrees 'above' the equator, but not looking directly 'south' but rather out on a angle towards the sun. This would have the rings disappear from view on your left side and converge due to depth perception on your right. From the seasons image I posted above, think of the view you would see if it were 2007, where the rings are not perfectly inline with the sun. You would be looking out at an angle, not directly 'south' and not directly 'east' but more ESE. I hope this is clear.

 

[Hurkyl]

My previous comments that the center must be straight down were due to the mistaken assumption we were projecting towards infinity. (e.g. a perspective drawn from a remote viewer) Projections to other points map ellipses to ellipses, they don't need to preserve the center.

Alas I don't have convenient tools to do the geometry to work out how the picture should look. Have you done the geometry or are you just eyeballing it?

(Of course, if it does turn out to be drawn correctly, it stills look weird. Sigh! )

 

[GoodUniverse]

Admittedly geometry isn't my best subject, so I am having to resort to my creative intuition/vision on this one. And I guess ultimately it is a very subjective thing... however I feel I have a good handle on the perspective here, so my last effort to plead my case is the illustration I have created below.

I think the BACK VIEW shows best how the rings would arch across the sky for the observer. Albeit, this is a perspective out behind the observer's position but I feel there would be a similar effect if viewed from the planet's cloud tops.

[PLAIN]http://www.gooduniverse.ca/blog1/wp-content/uploads/2011/01/uranus-persp.jpg

 

[Hurkyl]

Ah, I think your back view helps me see what I was trying to visualize!

One thing missing from your back view is that we the viewer aren't aligned with the observer. Try rotating the image counterclockwise until the observer is oriented vertically from our perspective, then zoom in on the observer.


You see the difference? I suspect the thing that was most bothering my eye was how the rings intersected the horizon -- they should meet it at an angle, rather than being nearly vertical.

 

[GoodUniverse]

Hurkyl, I am still struggling to see your point. Here is the orientation you requested. I have put the diagram over the scene that it is easier to match up. For me, the represented angles almost perfectly match, is there something I am missing?

[PLAIN]http://www.gooduniverse.ca/blog1/wp-content/uploads/2011/01/uranus-persp2.jpg

 

[Hurkyl]

It looks to me like the ring is already bending away from the line you drew -- and more seriously if you continued the arc, it would already be vertical by the time it reaches the bottom of the image.


I remembered I can do drawings in Java -- I've made an attempt to make a series of images taken from a spaceship flying in a straight line towards the surface, with rings roughly of the size and orientation you have drawn them. (45,000 km inner radius, 51,149 km outer radius, so roughly from the alpha to the epsilon ring)

(I just made the rings out of 11 circles -- I didn't try to make them correspond to the actual rings)

In the third image in the slideshow, the distance between you and the top of the planet is about the same as the radius of the outer edge of the rings. (So, obviously, most of the arc is not visible in the viewport) The last image is taken from the surface (Well, 1 kilometer above the surface).



The second image is if the rings all the way down to 32,000 km are visible, taken at the same place as the fourth image in the slideshow. (Your distance from the top of the planet is about a quarter of the radius of the outer ring)



The actual calculation I attempted to do is to place a flat rectangular viewing region in front of the eye, and for each part of the planet and its rings, draw a straight line from the eye to that part, and depict it on the flat viewing surface. The rectangle is about as far away as it is wide, and twice as wide as it is tall.

And, of course, I didn't bother trying to avoid drawing the parts of the rings that appear behind the planet.



The image started looking weird if I made the viewing surface too wide though -- I don't know how to account properly for the peripheral vision. The upper region of your image, I imagine, is in the region I'm not drawing. In any case, my images look weird to me too -- maybe rings are just naturally weird-looking to me.

 

[Hurkyl]

Here's the final image of the slideshow with the viewport 4 times wider in both directions. It looks weird to me, but not as weird as some of the other wide angle drawings I've made.

 

[GoodUniverse]

Hurkyl, I would agree that the arch may be going too vertical, too soon near the horizon. I will modify the artwork to have the rings more commited to its angle.
Thank you for your diligence, good work with the Java program. Perhaps one thing though that we can't calculate for is the gravitational influence on light near the horizon, similar to how the sun is more oblate during sunsets.
Also, I guess we would need to account for personal depth perception... I think the human eye is roughly similar to a 50mm camera lens? not sure about that.

 

[Hurkyl]

I hope it's useful. Clearly the original image looked good to people -- hopefully the correction looks good to more people. Of course, if I'm the only person in the world who thinks the original looks weird, it's probably better to leave it as. (I'm assuming your primary intent is something that looks good, but you're still trying to add as much realism as possible)


(and for the record, when I say it looks weird, I don't mean the entire image is bad -- I'm just commenting on the one aspect that caught my eye)

 

[GoodUniverse]

Yes, I am hoping for the most accurate depiction I can, so both scientific and artistic issues need to be addressed to the highest degree. So, thanks again for your sentiments.
Here is the new image.

[PLAIN]http://www.gooduniverse.ca/blog1/wp-content/uploads/2011/02/Uranus_v6a_web.jpg

 

[Sankaku]

I like it a lot - the new ring angle looks good to my eye.

The length of the meteor trail and the angle it comes in on seem at first to be connected with the rings. I had to do a double-take to figure out what it was. Is there a way to make it more obviously different than the rings? I don't know if anyone else had that reaction?

 

[GoodUniverse]

Sankaku, Actually the meteor is connected to the rings in a way... I have read that the rings of Uranus constantly drop debris into the atmosphere. This comes mostly as dust particles but also the odd larger object will also fall. So, the angle I have here is similar but I would agree with you that perhaps the length is too long. I am working on another revision now and will include this idea for next time. Thanks.

 

[qraal]

Hi GoodUniverse

That's amazing! I am very impressed. The fireball piercing the clouds is poetic license :-)

 

[EnumaElish]

Different yet almost familiar ("cosmic neighborhood") -- enchanting! Without art, science may be possible, but not as meaningful.

 

[GoodUniverse]

Thanks Enumafish,
Yes, familiar indeed... there is a similar look to the atmosphere that would make it seem like home (ie. blue sky, white-ish clouds) but the toxic clouds, ghostly rings, faint sun and extremely cold temperature would surely remind you that there was no place like home.

Incidentally, just a passing thought... with there being so much methane in the clouds, is the planet flammable? strange question I know, but thought I would ask.

 

[EnumaElish]

Enumafish? Is that an Ouranosian species? Regards,
EnumaElish
P. S. Enjoyed your description of the beautiful, suffocating atmosphere.

 

[GoodUniverse]

A thousand pardons EnumaElish... my brain just loves shortcuts.