NASA has a Pluto time website that shows how dark it is on Pluto at noon.

https://solarsystem.nasa.gov/planets/dwarf-planets/pluto/plutotime/

Noon on Pluto is comparable to 15 minutes before the sunrise on Earth. The landscape is therefore quite dark.

I have paid 20EUR for Space Engine and have done test to perhaps help them. Or I am doing something wrong, in which case please correct me. All tests are with the sun at the same angle and placed in the corner of the screen.

Auto mode:

Moon: 


Pluto: 

(As you can see both are as bright as Sahara sand dunes in desert summer noon on Earth)


HDR mode (the non-realistic rendering mode):

Moon: 


Pluto: 
(Pluto is still way too bright)


Manual mode (our final chance for realism):
Setting a manual light level on the lunar surface comparable to Apollo lunar surface photography and seeing what the surface of Pluto looks like at this same level:

Moon: 


Pluto: 

And this is what Saturn looks like facing the sun at that same light level


Saturn: 


Obviously Space Engine is wildy inaccurate.
What can I do to make Space Engine look accurate, apart from guessing what the brightness should be by adjusting it manually myself?

Possible temporary workaround:
Seeing as HDR mode seems to be the most realistic for now, perhaps it is best to set a manual exposure that is comparable to HDR, perhaps a little darker

PS: I'm a commercial advertising photographer and architect specializing in lighting. 

I understand that the human eye adjusts to light levels. Yet the human eye can still perceive differences in light levels (lx). We know that the surface of Pluto (at the brightest it can be) is similar to 15 minutes before sunrise on Earth, i.e. quite dark. Usually it is much darker when the sun is not directly overhead.

Yet the images I uploaded show the surface light on Pluto is nearly identical to the lunar surface which is obviously incorrect.
If we were to stand on Pluto (eventhough our eyes adapt) we would say "this place is a lot darker than Earth." Comparing the images in my post, we don't say this.

Seeing as you are as passionate about this as I, your SE settings must be different than mine as everyone can see that the effective comparison images I have posted are almost all identical in lighting. What settings do you use to get a realistic result?

Realistically this is what the surface of Pluto should look like at noon:



And like this at sunset:


Not this:

Noon on Pluto is comparable to 15 minutes before the sunrise on Earth. The landscape is therefore quite dark. Realistically this is what the surface of Pluto should look like at noon:

I don't think I agree. I don't think a typical landscape 15 minutes before sunrise on Earth looks that dark (that's near middle of civil twilight for most locations). But that figure also depends heavily on your latitude and season. The website tells me that my next "Pluto time" is only 6 minutes before sunrise, or a Sun angle of -1 degree. Furthermore, on Earth during twilight, the sky is much brighter than the ground, so your eyes adjust to the sky brightness, unlike on Pluto. So let's throw away the "x number of minutes before sunrise" comparison, and figure out how bright Pluto's surface is a little more precisely.

Pluto's current distance from the Sun is about 35 AU. Since we're comparing sunlight to sunlight, we can ignore spectral dependence, and calculate the lux on Pluto simply by the inverse square law. Direct sunlight at Earth provides illumination up to about 120,000 lux, so at Pluto this would be 120000/35^2 or about 98 lux. We may as well round to 100.

You might expect 100 lux to mean Pluto's surface should be comparable to a densely overcast day, or to something like bedroom lighting, or, sure, sometime shortly before sunrise. This is still quite bright enough to see clearly, and even to have full sensitivity to colors. But wait, it gets even better. There's one other factor we haven't accounted for yet: Pluto has a bright surface. Its bond albedo is about 0.72, which is more than twice as high as Earth's average (even with all the clouds), and six times higher than the Moon's.

Considering all that, I think your image representing what you think Pluto should look like at noon is actually way too dark. Something between that and the last image you shared (thinking it too bright) sounds more correct. Something like this, which is comparable to the brightness of my bedroom walls at around 100 lux. (My lights are on dimmer switches and I can summon a specific amount of lux to measure with a light meter.)



The brightness of Pluto's surface would also ruin your night vision such that you couldn't see the Milky Way at the same time, but whatever. 

Wow, this actually looks like some of the airless procedural worlds/moons in SE!  I guess SE did a pretty good job of indicating its surface brightness?  I wonder how the icy regions on Pluto look-- doesn't Pluto have a lot of ice on it-- even entire mountains made of ice?  I bet those would look absolutely spectacular!  And I wonder what the "heart" region of Pluto looks like from the ground?  And how large would Charon look since Pluto is basically a "double minor planet"? -- I still keep wanting to call it a planet lol.  And how much of a difference would be between day and night Pluto vs the night side of our Moon?

So if the Milky Way isn't visible on Pluto, can we say this is because of ground based light pollution?  In which case the sky should look brighter too because all that ground light is being reflected back up at the sky? So would a day or night on Pluto be more like a night in New York City or some other light polluted city? And how much of a difference would there be between a day on Pluto vs a night there?  Thanks!

And how much of a difference would be between day and night Pluto vs the night side of our Moon?

The dayside landscape of Pluto is darker than the Moon's, but you might struggle to tell except with a side-by-side comparison (especially because the Moon's surface is intrinsically so much darker, albedo only 0.12 on average.) On the night side, there is no difference except perhaps a very slight dimming of stars (I'm not sure if you would be able to notice it) near the horizon due to haze layers in Pluto's thin atmosphere.

You can absolutely see the Milky Way from Pluto's night side, as long as Charon is not in the sky.   You could also see the Milky Way from Pluto's day side, if you avoid having the Sun or any part of the landscape in your field of vision for a few minutes so that your eyes can adapt to the sky darkness properly.

Another fun comparison to Pluto's landscape brightness during the day: 100 lux is approximately the illumination about 30 seconds before the totality of a total solar eclipse (for a typical 2-minute duration totality.) This is much darker than ordinary daytime, but also much brighter than I think most people expect (it still feels more like daytime than nighttime, or more like the approach of a very weird twilight with the apparent light level changing rapidly). The illumination during totality itself (again for a 2 minute totality) is around 10 lux.

And how much of a difference would be between day and night Pluto vs the night side of our Moon?

The dayside landscape of Pluto is darker than the Moon's, but you might struggle to tell except with a side-by-side comparison (especially because the Moon's surface is intrinsically so much darker, albedo only 0.12 on average.) On the night side, there is no difference except perhaps a very slight dimming of stars (I'm not sure if you would be able to notice it) near the horizon due to haze layers in Pluto's thin atmosphere.

You can absolutely see the Milky Way from Pluto's night side, as long as Charon is not in the sky.   You could also see the Milky Way from Pluto's day side, if you avoid having the Sun or any part of the landscape in your field of vision for a few minutes so that your eyes can adapt to the sky darkness properly.

Another fun comparison to Pluto's landscape brightness during the day: 100 lux is approximately the illumination about 30 seconds before the totality of a total solar eclipse (for a typical 2-minute duration totality.) This is much darker than ordinary daytime, but also much brighter than I think most people expect (it still feels more like daytime than nighttime, or more like the approach of a very weird twilight with the apparent light level changing rapidly). The illumination during totality itself (again for a 2 minute totality) is around 10 lux.

Thanks Wat-- I also figured that 100 lux on Pluto would look different than 100 lux on Earth because of the atmospheric differences.  For example I don't believe you can see any stars in the sky 30 seconds before totality during a total solar eclipse?  They only pop into view during actual totality I think?

I was also wondering how bright Charon is when viewed from the surface of Pluto and how close is it to the brightness of our own Moon from Earth?  Charon and Pluto are tidally locked to each other aren't they?  Would that mean certain parts of Pluto never get to see Charon and some parts of Pluto always have it in their sky?   I guess a total solar eclipse on Pluto via Charon would look more like a stellar occultation?  If it ever even happens (because of Pluto and Charon being tidally locked)?  And a total lunar eclipse would make Charon almost completely black because of how small the sun looks from there plus the very thin Plutonian atmosphere? I take it if there can be total solar eclipses there there can also be total lunar eclipses but if one can't occur the other can't occur either?  The two are always linked on Earth and I'm sure the same is the case on Pluto. 

Allright, I think this is a nice demonstration. Probably the best I can think of. Using the above measurements of lux vs. time through a total solar eclipse, a Pluto equivalent illumination happens about 30 seconds before and after totality. (We can confirm this by considering the fraction of the solar disk still exposed, which is approximately 0.1% or so. Actually, a bit more than that, but after accounting for the limb darkening effect on the Sun it's equivalent to about 0.1%) This point of a solar eclipse is a much better analogue than twilight, because the Sun is still high in the sky and providing most of the illumination directly, only about 99.9% weaker, just like on Pluto itself. The sky contributes light as well, but only about 10 lux versus 100.

Here's a frame from midtskogen's video of the 2015 solar eclipse in Svalbard. The frame is 30 seconds before totality, and the icy landscape is a better analogue for Pluto's surface than most other terrain on Earth.



Same test with my video from the 2017 eclipse in Madras, Oregon. The hood of the white vehicle in foreground is now the analogue for Pluto's surface at noon.

For example I don't believe you can see any stars in the sky 30 seconds before totality during a total solar eclipse? 

You can see Venus very clearly long before that (though you can also spot it with difficulty in broad daylight), and probably a few of the brightest stars if you know where to look. I didn't really try to look.

 I guess a total solar eclipse on Pluto via Charon would look more like a stellar occultation?  If it ever even happens

Yes, and they do happen sometimes.

Wow this is spectacular and also gives me some idea what to look for next year during the total eclipse!  Thanks so much, Wat!

It looks otherworldly even before totality!

The most I have ever seen is a 90% partial eclipse and that was many years ago (May 1994) and it was mostly cloudy that day with just a peak of maximum eclipse through the clouds.

100 lux is quite a bit more than what is used for a well lit highway, and can you see the Milky Way when driving on the highway?  No, and you wouldn't easily see it on Pluto either, even assuming that there is no atmosphere brightening the sky.  The eyes need time to adapt.

The eclipse analogy is pretty good.  Just before totality the sun is getting close to being a point source and the shadows become very sharp, and on Pluto the sun appears very small in the sky and shadows will similarly be sharp.

That sounds very interesting, I wonder if that means there is no penumbral shadow?

That sounds very interesting, I wonder if that means there is no penumbral shadow?

There is a penumbral shadow, it is just extremely narrow (the width of the penumbra opens with the same angle as the apparent diameter of the Sun as seen by the object casting the shadow). At Earth this is half a degree. On Pluto it is 0.015 degrees or 0.9 arcminutes. Charon is about 19,000km away from Pluto, so the penumbral shadow of Pluto cast on Charon is about 5km wide. (This being the region where if you were standing on Charon, just part of the tiny disk of the Sun would be eclipsed behind the edge of Pluto.)

Standing on Pluto or Charon, the width of your own penumbral shadow on the ground would be about half a millimeter. Sharp shadows, indeed, and the final minute of a total eclipse gives the same effect (but sharper in one direction than the other because of the Sun turning to a very thin crescent.)

Wow this is fascinating, Wat....how wide would the area under a total solar eclipse be on both Charon and Pluto?

Half a millimeter wide penumbral shadow sounds surreal....I hope when shadows get done on SE we'll be able to see this (on rocks and mountains/hills/cliffs of course, but maybe we could see this with shadows of ships and "astronauts" too?)

Two shadows cast by the same object. One fuzzy, one sharp.  This is from .9.8.0.

Wow this is fascinating, Wat....how wide would the area under a total solar eclipse be on both Charon and Pluto?

Nearly the same as the sizes of Pluto and Charon themselves. Their umbra shadow diameters only shrink by about 10 km across the distance between the two.

The Sun doesn't seem to change according to the inverse square law when going from planet to planet.  4% of Earth's sunlight as Jupiter, 1% at Saturn, 0.25 % at Uranus and so on...just don't see a huge difference between them...Saturn doesn't seem to have 25% of the light that Jupiter does..I hope this can be remedied