Planetary illumination

[drew]

It is literally physically and mathematically impossible for any other star to illuminate only half of a planet, even if it is just by an immeasurably small amount. Stars are always bigger than planets, therefor will always cover more than half the surface, no matter the distance.
Obviously disregarding weird potato planets and as said before neutron stars and white dwarfs, since these can be smaller than planets.

I entirely agree with that, but the images in the OP have no explanation other than that the modelling is incorrect. The terminator curving in that way from a sun at range is not what you would see in 'real life'. The fraction of the illuminated surface of the worlds is way too high even correcting for perspective. The fraction should be a matter of minor percentage over 50% unless the planet is in an extremely close (and probably tidally locked to boot) orbit.

Cheers,

Drew.

 

[BEKTOP 3APEMOB]

ninja'd

Spoiler

There's a straight terminator line on the moon. We can see it like that on occasion

 

[Commander William Diffin]

Look, it's quite simple. IRL a light source on one side of a sphere can never illuminate more than 50% of the sphere. The other 50% is always entirely in the shadow of the lit 50%.

But in answer to your arguments: neither the nature of the light source nor perspective have anything to with it. Imagine the planet isn't a planet but a flat disc of equal diameter to the planet. No matter how big the star is in front of the disc, every part of that star is completely obscured to everything immediately behind the disc. None of its light shines behind the disc. There is no way around the disc for the light. So light rays from a star incident on a planet always behave as though they run parallel to the line joining the centre of the star and the centre of the planet. There is no way they can shine down over the top of or under the bottom of a planet, no matter how big the star is or how close in to it the planet is. That's not an assertion, that's just how the observable fact that a single star never illuminates more than half of a planet at a time is explained. And for perspective to make a half-illuminated planet look more than half-illuminated, the observer would have to be closer to the lit side of the planet than the dark side, in which case perspective would make the terminator line between the light and dark appear curved and not straight at all anyway. Obviously.

Now take a look at Cmdr Spanksh's screenshot from some free simulator he downloaded from some amateur programmer somewhere:


You can see that the terminator line is vertically straight, and cuts the planet unequally in two. If you look closely it curves at the top and bottom of the planet as if suddenly changing direction for no reason and impossibly cutting even further into the unlit side of the planet on the far side of the view, presumably in an attempt to simulate atmospheric light scattering. But if you ignore that, logically the vertical terminator line must extend all the way around the planet in the same plane (what else can it do?) so that when viewed from exactly the other side from the same distance, the planet's illumination appears identical but laterally reversed, like so:


This is of course impossible. There is no way that the terminator should appear vertical unless the observer is looking from directly above it, so the terminator runs straight through the middle of the circle the planet presents to the observer, cutting it clean in half. Plainly the simulation used to produce Cmdr Spanksh's image is wrong as well as that used in ED. Perhaps they're using the same budget algorithm. The point being amateur simulations prove nothing. I challenge anyone to find a single photograph of any planet or moon IRL which shows such an illumination as in Cmdr Spanksh's simulated screenshot. And it's no use trying to bully me into conceding the point even though I'm right. This is the Internet. You can't touch me.

Seriously, take it from me, I'm an astronomer, and I have never seen anything in Outer Space lit up like that. It's simply not possible. Believe me. I know all about what planets look like under different illuminations, indeed I've trained myself to recognize every slight disturbance in a terminator line that might indicate something going on in a planet's atmosphere or on the surface. And they look nothing like what you see in ED, nor in Cmdr Spanksh's simulations. I know what I'm talking about. In an annular Solar eclipse, you don't see some of the half of the Moon facing away from the Sun still lit up in a ring around the edge do you now. Similarly in a transit of Mercury or of Venus, even with Venus' thick atmosphere. QED.

So can I get a moderator's opinion and an answer to my tickets now? The game's great and everything, but every time I see the planets lit up all wrong in a realistic recreation of the Galaxy it kinda breaks the immersion y'know what I mean? It's not a difficult fix. Ask DB about the following line of BBC BASIC code, as used by the BBC Microcomputer which ran the original Elite. It draws a silhouette of a globe for any percentage of illumination. I wrote it myself to make templates of Venus and Mars to draw on whilst I'm observing them at the telescope.

MO.0:I.'"PHASE (%):"P=(50-P)/50:CLS:MOVE640,0:F.X=(0-(PI/2))TO(PI/2)S..1R.640+(512*COS(X)),511+(512*SIN(X)):N.:F.X=(PI/2)TO(0-(PI/2))S..1R.640+(512*P*COS(X)),511+(512*SIN(X)):N.

 

[Chaodiurn]

You know that something's wrong when you see a ringed star cast a shadow on its ring because it blocks the light of the sun it orbits.

 

[Spanksh]

Spoiler

Look, it's quite simple. IRL a light source on one side of a sphere can never illuminate more than 50% of the sphere. The other 50% is always entirely in the shadow of the lit 50%.

But in answer to your arguments: neither the nature of the light source nor perspective have anything to with it. Imagine the planet isn't a planet but a flat disc of equal diameter to the planet. No matter how big the star is in front of the disc, every part of that star is completely obscured to everything immediately behind the disc. None of its light shines behind the disc. There is no way around the disc for the light. So light rays from a star incident on a planet always behave as though they run parallel to the line joining the centre of the star and the centre of the planet. There is no way they can shine down over the top of or under the bottom of a planet, no matter how big the star is or how close in to it the planet is. That's not an assertion, that's just how the observable fact that a single star never illuminates more than half of a planet at a time is explained. And for perspective to make a half-illuminated planet look more than half-illuminated, the observer would have to be closer to the lit side of the planet than the dark side, in which case perspective would make the terminator line between the light and dark appear curved and not straight at all anyway. Obviously.

Now take a look at Cmdr Spanksh's screenshot from some free simulator he downloaded from some amateur programmer somewhere:
View attachment 76064

You can see that the terminator line is vertically straight, and cuts the planet unequally in two. If you look closely it curves at the top and bottom of the planet as if suddenly changing direction for no reason and impossibly cutting even further into the unlit side of the planet on the far side of the view, presumably in an attempt to simulate atmospheric light scattering. But if you ignore that, logically the vertical terminator line must extend all the way around the planet in the same plane (what else can it do?) so that when viewed from exactly the other side from the same distance, the planet's illumination appears identical but laterally reversed, like so:
View attachment 76065

This is of course impossible. There is no way that the terminator should appear vertical unless the observer is looking from directly above it, so the terminator runs straight through the middle of the circle the planet presents to the observer, cutting it clean in half. Plainly the simulation used to produce Cmdr Spanksh's image is wrong as well as that used in ED. Perhaps they're using the same budget algorithm. The point being amateur simulations prove nothing. I challenge anyone to find a single photograph of any planet or moon IRL which shows such an illumination as in Cmdr Spanksh's simulated screenshot. And it's no use trying to bully me into conceding the point even though I'm right. This is the Internet. You can't touch me.

Seriously, take it from me, I'm an astronomer, and I have never seen anything in Outer Space lit up like that. It's simply not possible. Believe me. I know all about what planets look like under different illuminations, indeed I've trained myself to recognize every slight disturbance in a terminator line that might indicate something going on in a planet's atmosphere or on the surface. And they look nothing like what you see in ED, nor in Cmdr Spanksh's simulations. I know what I'm talking about. In an annular Solar eclipse, you don't see some of the half of the Moon facing away from the Sun still lit up in a ring around the edge do you now. Similarly in a transit of Mercury or of Venus, even with Venus' thick atmosphere. QED.

So can I get a moderator's opinion and an answer to my tickets now? The game's great and everything, but every time I see the planets lit up all wrong in a realistic recreation of the Galaxy it kinda breaks the immersion y'know what I mean? It's not a difficult fix. Ask DB about the following line of BBC BASIC code, as used by the BBC Microcomputer which ran the original Elite. It draws a silhouette of a globe for any percentage of illumination. I wrote it myself to make templates of Venus and Mars to draw on whilst I'm observing them at the telescope.

MO.0:I.'"PHASE (%):"P=(50-P)/50:CLS:MOVE640,0:F.X=(0-(PI/2))TO(PI/2)S..1R.640+(512*COS(X)),511+(512*SIN(X)):N.:F.X=(PI/2)TO(0-(PI/2))S..1R.640+(512*P*COS(X)),511+(512*SIN(X)):N.

Okay and exactly that's why I said you are wrong and will always be wrong. The issue here is not that your thought process is inherently wrong, but the basis of your arguments is flawed. You always assume the light source is a point source, which it isn't. If you have a light source bigger than the object, the shadow of said object will always be smaller than said object. Therefor a round object will always be illuminated more than 50%.

I will post my picture again, since you apparently skipped it:

And here another one explaining it better (Not pretty but functional):


As said this is the "acceleration stays constant"-thread allover again. Not trying to be rude, but just do yourself a favor and google it (specifically the subject of tangents. If you understand them, you'll understand the whole issue here). Also calling yourself an Astronomer doesn't give you the right to disregard basic mathematics and geometry - which btw. are a requirement for Astronomy, which is more than looking at pretty pictures of glowy things in the sky. Remember when our math teachers told us we will need that stuff later in life and nobody believed him? THIS is that time.


"And it's no use trying to bully me into conceding the point even though I'm right. This is the Internet. You can't touch me." - Says pretty much everything about your credibility Mr. Astronomer on the internet, who ignores basic math.
"Seriously, take it from me, I'm an astronomer, and I have never seen anything in Outer Space lit up like that. It's simply not possible." - I have never seen buildings higher than 10 floors personally, therefor Skyscrapers don't exist. They are simply not possible. Seems about right.
How many planets are actually visible to us again and how many different suns and different planets do we have as a real example again? Right.

Well either way I'm out of this discussion. People who actively deny having something explained to them by simply skipping over all arguments several people present are not those I want to spend my time on. Have fun, believe what you will and enjoy sending tickets for non-bugs.

 

[BEKTOP 3APEMOB]

You know that something's wrong when you see a ringed star cast a shadow on its ring because it blocks the light of the sun it orbits.

I think this is perfectly normal:
The amount of light that is reflected from parts of such rings that are illuminated by both stars is bigger than the amount of light that is reflected from parts of rings illuminated by a single star. So you can actually perceive this difference with your eyes and it should look like a shadow.

If this shadow looks completely dark, then it might have to do with the difference in amount of light these parts get.
Take this pic for example:

A and B squares have the same brightness and color, but our brains perceive them as different, because of how they play with contrast here

 

[Kicks]

Whether or not the shadowing is correct, I think OP needs to check his attitude in at the door. It's all good and well to have a discussion about accuracy or inaccuracy of a lighting simulation, but you're tone is that of someone who'd never be allowed in a meeting, perhaps not even near the door.

 

[rcdcce]

I consider myself pretty critical of ED graphics but not in the sense they are making big mistakes or putting no effort in. More they have created some of the most beautiful scenes in my gaming memory so it's unfortunate when some things aren't quite right and the illusion fails. This one however has never even registered as a problem for me. Even if the accuracy can be questioned in some odd cases it looks 99% great! I agree with the points regarding multiple lighting as well. If ED were to implement it now they would be dropping a serious weight on the overall game fps, even at the high end which would make other graphical decisions harder, some of which might be of greater value. There's no reason to think these things couldn't happen in the near future but video cards are still coming to terms with dynamic lighting and shadows.

 

[Baleur]

You guys realize you cant use solid 3d spheres in 3d apps to demonstrate this, right?
The op was talking about atmospheric planets. Atmospheres scatter and "carry" the light further. Indirect illumination.
Thats why we have sunsets and sunrises while the sun is below the horizon. Granted they dont last very long / carry the light very far, but its still there.
And no solid 3d sphere or cylinder will ever represent that if you dont add an atmosphere around it that scatters the light.

I don't mean to rub it in further but... we don't really need computer simulations to illustrate my point. All you have to do is go outside at night and look up at the sky, every night, for twenty eight days. You'll see the moon provide a wonderful example of perspective.

http://astropixels.com/moon/phases2/images/Phases10-5x3w.jpg

Yeah but the moon also doesnt have an atmosphere to slightly scatter the light further onto the "dusk/twilight" side.
Granted, its not a huge effect, but its there. If earth didnt have an atmosphere our sunsets wouldnt exist, it'd just go pitch black immediately as the sun dipped below the hills.
Now, how far from a planet this is actually visible, i have no clue. But the OP is definetly right. Its just a matter of how noticeable it really is in reality. Maybe its just a few degrees.