In Dune 2 (2024), the planet Giedi Prime (home of House Harkonnen) features a “black sun”. The sun generates only shades of grey as its “colors”. Is such a black sun actually possible? If so, what element(s) would it be burning to achieve such an effect? Or is it all just science-fiction make-believe?
[I’m not sure this is the correct category so let me know if I need to move it.]
The final stages of a Red Dwarf might be a contender.
Maybe, but it would take many trillions of years for that to take place.
“Grey” is simply white at a lower intensity. White is a uniform mixture of all visible wavelengths. Any surface in a white light with a non-uniform reflectivity will have a hue. Thus, there can’t be a sun that imposes greyscale.
I can think of two ways to achieve a greyscale world. First, everything in the world would have to uniformly reflect all visible wavelengths. That is, paint everything grey.
Or, second, the inhabitants of the world would have to be colorblind. Thus, the inhabitants would perceive everything as grey.
If you want normal humans and normal objects in the world, you cold also just have a very faint sun. We don’t perceive colors very well in low light conditions. Though the inhabitants of that world could still just use artificial light sources of whatever brightness they want.
Any star will be close to a blackbody radiator with a distribution defined by the temperature of its photosphere. Certain wavelengths are blocked by different elements and molecules in the atmosphere, but in order to be “grey” light would all have to be selectively blocked such that the colors only appear as shades of uniform white. In sufficiently dim light everything looks basically grey (because there isn’t enough light to activate photoreceptors cones of the of the eye), but that would mean that everything is generally dim. A star with a peak output in the near-ultraviolet (>7000 K) would tend to oversaturate the visual receptors making everything look white, but few things would look dim in that case, and the blue-white stars (A type in the Harvard Classification System) are unlikely to form Earth-like rocky planets in their habitable zones for a number of reasons.
Red dwarf (Class M main sequence) stars are the most numerous stars in the current Universe but their even marginally habitable zones are very close to the stars, and most are variable stars with a large amount of flare and electromagnetic activity, making them unlikely hosts for livable terrestrial planets. The light from these suns would be mostly in the infrared, and would basically be like living at night. A red giant star (off the main sequence, as our sun will be in another four billion years) would be visibly red with most of the other colors of the spectrum looking very dim to our eyes (essentially grey). My guess would be that the star of Giedi Prime is a late-ish K-spectral type III luminosity giant star similar to Arcturus with enough infrared output to keep the planet habitable but very dim, and everything is colored in reflective pigments to maximize visibility.
Stranger
Would a star with a particularly bright pure color that’s much more intense than it’s other colors work? In humans, at least, if you expose them to red light cone fatigue sets in and you get gray (from rods). Trying wearing good red filters for a while.
Again, a star is nearly perfect blackbody radiator, and so it will have a spectrum defined by Planck’s Law and the photosphere temperature. (They will have distinct spectral absoprtion lines from the dominant atomic constituents, but otherwise will distribute radiated energy as a thermal blackbody because that is literally what it is.) Stars cannot have a “bright pure color” or other narrowband emission, although they will have a peak that will tend to dominate, especially as you go up the Harvard Stellar Classification Scheme (which was essentially created by astronomer Annie Jump Cannon, who along with Henrietta Swan Leavitt and Jocelyn Bell Burnell laid much of the groundwork for modern observational astronomy, but that is another topic) toward the B, A, and rare O class stars. In theory, you could have a planetary atmosphere (not including clouds) that absorbs all but one narrow band of visible spectra but that would be unlikely to say the least. A star with peak emissions in the near infrared, however, is going to produce an ambient light where everything is reddish, but also very dark in general.
Stranger
Is OP hoping to wash away the rain?
Regardless of whether or not it’s possible, that part of the movie was one of the few times I’ve seen a blatant change from the source material that I thoroughly enjoyed. It made for such a unique visual.
O-type stars put out largely actinic UV. But they’re blue-white, not black.
The actual visuals in Dune were using IR pass filters, it looks like (I love IR photography)
We’re talking about a Science Fiction context where interstellar space travel, guided by creatures who eat Spice, is possible. The Rules of our Universe don’t necessarily apply.
Could there hypothetically be a star unlike ones we are familiar with that have a special composition that results in an odd spectrum? A “sodium star” which is hot mainly due to gravitational collapse plus internal radioactive heating would, in visible light, have just the famous twin yellow lines. Then one could have humanoids with cones sensitive to yellow and the rest of my point might follow.
Some flexible thinking is clearly allowed here.
The novels, at least, were supposed to be set tens of thousands of years into our future with technological advancements consistent with that. They were written in the 60s, so the idea of “mind expanding drugs” (among other facets of the story) was taken much more seriously.
In that context, I don’t think Giedi Prime, as presented, makes sense.
On the other hand, it’s pretty clear Villaneuve took a few creative liberties with source, so, sure, toss out harder science explanations, at least for the movies. That’s in line with his other films, too. It’d be hard to make some of those novels filmable, otherwise.
I saw an article that he wants to do “Rendezvous with Rama” (certainly closer to the hard end of classic SF), and I have no doubt he’ll fudge any science he must to make something filmable.
Perhaps so, but maybe the B&W scenes were set sometime before the 1930s:
“Black Hole Sun” is clearly describing the perception that a large language model has of stellar magnetohydrodynamics after being fed The Manga Guide to Astrophysics.
In fiction you can postulate anything you like, but a “sodium star” which is radiating due to “gravitational collapse plus internal radioactive heating” in a visual spectrum is not physically plausible. For what it is worth, while the Holtzmann Effect which enables all of the exotic technology of Herbert’s Dune universe and the precognative abilities of the “spice” and “Water of Life” are clearly literary conceits that he doesn’t really make any effort to explain, the ecology and physical environment of Arrakis are reasonably well-grounded in existing science.
He also took substantial “creative liberties” with the story and characters, sometimes in ways that are contrary to Herbert’s themes. Villaneuve makes beautiful looking movies but he doesn’t seem inclined to preserve the intent of the source material even within the bounds of making changes to adapt to film.
Stranger
Yeah, so the answer is basically: mostly SF movie magic which, as usual, can be fanwanked into something somewhat resembling plausible.
Ditto “Arrival” / “Story of Your Life”
Which is why I’m rather curious what he does with “Rendezvous with Rama”. I imagine a lot more conflict and violence and maybe geopolitics than the original, which was mostly a straight adventure/exploration piece.
It has been a long time since I’ve read Rendezvous with Rama but while there are some individual scenes that could obviously invite expansive visuals, overall it didn’t have a lot of plot or strong characters, and Clarke seemed mostly interested in presenting a ‘realistic’ first contact experience in which the conflict comes from trying to understand and interpret the motivations of the builders and their biot creations. The subsequent novels (especially those cowritten with Gentry Lee) had a lot more manufactured plot devices and character conflict, albeit not to the improvement of the stories. Still, as long as Villaneuve doesn’t mangle it as badly as David Goyer trashed Foundation, it will at least be a sumptuous visual experience.
Stranger
I figure the main thing about Giedi Prime is not that the solar radiation is particularly exotic, they just have a lot of smog. Like, a lot. Don’t expect to do much skywatching. Wearing a respirator mask is a good idea.
“Well-grounded” in exactly the same way as any other perpetual motion machine. The entire ecology is worms all the way down, with no photosynthesis or anything analogous to it anywhere to be found.
So Tremors writ large?
Maybe they eat primordial petroleum (or the local equivalent) they somehow locate deep underground. For few enough worms that might sustain them for hundreds of millennia.