8/18 Today would normally be a writing day, but I needed to spend all day on the painting in order to have something I was willing to show T. the next day.
Continuing to paint the planet: I used titanium white, cad yellow med. & deep, titanium buff, and naples yellow to make it more yellow and give more distinct bands of striation (though I liked the striation enough that I didn't want to fully cover it!). Then I remembered Indian yellow, another transparent warm color, which gave the more golden quality it needed. I used more transparent iron oxide glazes and a little burnt umber to create a sense of depth in the surface layers, and to create the shadow to make it look like a globe not a flat disk.
As I worked, more visual logic questions assailed me: would the planet look that large in the sky, and that visible in daylight? No clue. Shouldn't it be casting a lot of yellow light on the snow also? Probably, but I really wanted to keep the ground as cold and stark as possible, and I already had a lot more color in this than T. and I had discussed. Sometimes design wins over logic.
I did some more work with cloud greys. How do you model clouds but not make them look dirty? It remains a problem. Then I tried some pale yellow on the inner ring of clouds, where the planet would cast warm light... no good. The pastel yellow was too sunset-pretty.

To make it more lurid and ominous, I added cad orange and Indian yellow. My tentative logic was that the light is on the rim of the clouds; the darker cloud system is closer to the viewer...but I suspected the dark rims should actually be light too. To quote Joni Mitchell: I really don't know clouds at all!
Avoiding the cloud problem, I put mountain shadow on the frozen lake and the snowy slopes around it, using the same blue/grey mix as in the clouds, then glazes of phthalo or white as needed to soften the edges. Adding that small amount of modelling really helped this feel more like a scene to me, a coherent receding space. Heading diagonally in the right direction?
However, I now realized the problem in painting with gesso after the initial stages: it’s flatter than the paint, so shows as matte spots on the snow. Oops. I covered that with titanium white for an even shine.
Back to the clouds: I mixed a really dark payne's grey to give more dramatic contrast. In retrospect, I can say that right about here is where I really went terribly wrong:

I soon realized that these edges are way too dark, and way too smooth: cumulus cartoons. I was modelling the edges too uniformly, as if these were smooth globs instead of loose water vapor. I kept hacking away at it, but couldn't make it right. Yet in each of my frustrated stages I can see an inkling, a little zone that did work, among an overall effect that did not. I'm really glad I took all the process photos, because thus I can extract those little bits for future reference. (The photos also helped show me that some progress actually was happening.)
It's a frustrating and scary thing about painting that there is no "save as" or "undo" command. With acrylics, especially, the ability to cover over previous layers is both a blessing and a curse: easy to fix, easy to obliterate something good, and (unlike watercolor) no built-in requirement to stop at a certain point instead of reworking it to death. In writing, you can change a draft, but as long as you saved a previous version, you can restore it exactly just by putting words back in that order: an exact correspondence of signified and signifier. In digital art, you can at least save and restore the stages or elements. Here, there is no fully going back to what was there before. Sometimes what you had before was better, sometimes it wasn't, but you won't really be able to tell until it's too late to go back...

A couple hours later, I finally concluded that this sky was too much for this picture, too dark, pulling too much attention to the background. That’s a problem with the planet too, but at least it looks convincing. There’s no reason for all these dark dramatic edges; these clouds should be light on the edge, and they’re snow clouds, not rain clouds. If this was just a sky painting, I could maybe live with it, but the figures need to be the focus of the image. Bah.
Some words of Michael Whelan kept coming back to me: "The trick is not to get your first illustration job, but to get your second job after you've blown your first..."
Casting despondently about, I turned to an Andrew Wyeth art book in the hope that he could show me how to paint clouds. Actually, it turns out he mostly paints flat overcast skies; not a distinct cloud to be seen. But I did find this trenchant Wyeth quote about his painting process:
“I can’t control it. If I control it, it’s no good.”That’s
Andrew freaking Wyeth, the painter who has done some of the most meticulous, exquisitely detailed paintings of our era. A painter who often works in egg tempera, an extremely painstaking and finicky medium that does not accommodate a fast or loose approach. “I can’t control it.” Okay, then...
This is true in dance, in martial arts, in many other arts: in order to flow effectively, you have to relinquish control. But in order not to end up with an uncoordinated mess at least some of the time, your non-controlling must come from a place of deep knowing. There's the rub.
Pondering this, I took a dinner break, and went to National Geo for more photo references, which showed me how my cloud edges were much too crisp, simple, and defined, and how clouds are often dark ones against light ones or vice versa, less often a complete dark-to-light shading on one form.
Triggered by the ‘don’t control it’ concept and my extreme frustration, I returned to the painting and had a breakthrough (or a breakdown? or something). First I wanted to tone down the Dark Cloud Edges with some white glazes, but zinc white alone wasn’t covering at all. So I mixed a big pool of both titanium and zinc whites (splitting the difference of opacity) plus lots of Open gel to keep it blendable for a while. But instead of carefully glazing this in my usual manner, I slapped some paint on with a filbert brush, then rubbed it around with a rag. That seemed promising: softer, more atmospheric, no discrete brushstrokes getting in the way. I threw caution to the winds, attacked it, blobbed, blotted, smeared, wiped on, rubbed out, literally finger painted... god, it felt great! I made diagonal finger strokes for the effect of blowing snow, hazed out the edges, then brought some of the darks back by rubbing paint off, but let them stay streaked by white... A mess? Maybe. But I experimented, went out on a limb, out of desperation. I might have just created a bigger mess, I couldn't tell, but at least I tried something different. That... was really interesting.
Mind you, there were aspects of the version before that I liked better than what I had now. But sometimes you have to let go a piece of good material that doesn't fit the rest of the piece. As writers say, Kill your darlings...

I worked more on the snowy hills, creating contours and softening transitions; I finally subdued the heavy phthalo outlines with subtler grey-blue ones. The snow-trail behind the figures was coming along, rendered in various tints of blue.
Till recent years, I had never used filbert brushes (flat with a rounded tip), so I haven't really incorporated them into my repertoire. But on this piece I’m liking the filbert for rendering clouds and snow; it covers broadly, but gives more organic marks, whereas the round leaves distinct brushstrokes, often ridged, and the flat makes chunkier edges.
Given the backlighting, I realized that the foreground snow slope (where the red man is about to walk) would be in shadow. I lightly rubbed on some phthalo there, but decided that just muddled the snow effect. I ended up putting titanium white back over it (though I let hints of the blue show through to create a little dimension). I did an awful lot of back-and-forthing on this piece.
I put a tidge more shadow on the yellow man, though I still hadn't painted him in detail. At the last minute, past my work-night bedtime, I realized I hadn’t done anything about the planet's ring... I sketched it in with white just to show T. where it would be, but I knew the shape wasn’t right yet. After the next photo was taken, I added the bent antenna and broken wires to the communication device (which helped it stop looking like a TV remote). I now felt I could bear to show this to T., with the caveat that it's not done. (For instance, I still hadn't specified the shape of the spaceship at all.)

8/19 In the light of day, the clouds looked better than they had last night. Not quite there, but... not as far off as it had seemed. Overall, I feel it is an arresting image. If I saw it across a room, I’d go look at it. The question was, what would T. think of it?