Unrealistic Solar System Lighting

[guest]

"The beauty of Celestia is its accuracy. The image in front of you is exactly what you would see if you were really positioned in space at that very spot right now."

One thing that i dont find very accutate is the way light from the sun doesn't lose intensity the further it travels. If you look at Mercury and then Pluto they are just the same brightness. In fact, pluto should be nearly black. It took a 30 sec. exposure to get that nice picture of neptune from voyager because its so dark. Now of course there should be a setting to turn this realistic lightin on/off.

[tommy sixpix]

I am still fairly new to this wonderful program, but...have you tried turning off "ambient light"...


tommy sixpix

[guest]

you sure are new to this program. Ambient light it just light that illuminates the dark side of planets, i am talking about the light from the sun. and yes, it is off, it has been off the whole time.

[tommy sixpix]

My appologies...perhaps you may help me...what is a good or average setting for the amount of stars visible? Again, I appologise for my ignorance...

tommysixpix

[granthutchison]

One thing that i dont find very accutate is the way light from the sun doesn't lose intensity the further it travels. If you look at Mercury and then Pluto they are just the same brightness.

Your computer monitor doesn't have the range of brightness available to simulate the range of brightnesses that exist in the real world; but fortunately your eyes are quite good at adapting to various levels of brightness without you noticing.
So the thousand-fold difference in illumination between Earth and Pluto would mean you couldn't see Pluto on your monitor screen if Celestia attempted to duplicate it - which would be entirely unrealistic. In fact, the illumination at Pluto's current distance from the Sun is about 150 lux - about the same as a hotel lobby. You couldn't take photographs by ambient light, but you'd be able to see it very well indeed.

Grant

[Gordon]

My appologies...perhaps you may help me...what is a good or average setting for the amount of stars visible? Again, I appologise for my ignorance...

tommysixpix

hello tommy,

if i may advise you, you should really have a look at Frank's celestia user guide which will give you all the information you need to start with Celestia and all its (her, his ?) feature.

http://ennui.shatters.net/celestia/documentation.html

bye

G.

[granthutchison]

what is a good or average setting for the amount of stars visible

If you set your magnitude level to around 6 this should duplicate what you'd see with a moderately dark-adapted eye. Some people can see down to 6.5 or beyond if they spend a long time adapting in a very dark environment.
But if you are in orbit around a bright planet, you should actually see far fewer stars as you look towards the planet, because the light from the planet keeps your pupils constricted.

Grant

[Guest]

One thing that i dont find very accutate is the way light from the sun doesn't lose intensity the further it travels. If you look at Mercury and then Pluto they are just the same brightness.

Your computer monitor doesn't have the range of brightness available to simulate the range of brightnesses that exist in the real world; but fortunately your eyes are quite good at adapting to various levels of brightness without you noticing.
So the thousand-fold difference in illumination between Earth and Pluto would mean you couldn't see Pluto on your monitor screen if Celestia attempted to duplicate it - which would be entirely unrealistic. In fact, the illumination at Pluto's current distance from the Sun is about 150 lux - about the same as a hotel lobby. You couldn't take photographs by ambient light, but you'd be able to see it very well indeed.

Grant

Whats so unrealistic about pluto being to dark that you cant really see it, that the way it is in real life. and if you look at the quote at the top of the page from the celestia documents, thats the way it should be. and to further show that light does not lose intensity the further it travels from the sun is to look at voyager 1 in th year 20029, when it is about 1 lightyear away from the sun, and it is the exact same brightness as it was when it was launched in year 19-whatever. Of course it wouldnt be fun if you couldnt see it because its so dark, but you could use the ambient light seeing to fix that.

[granthutchison]

Whats so unrealistic about pluto being to dark that you cant really see it, that the way it is in real life.

No, it isn't like that in real life. That's my whole point - if you were in orbit around Pluto right now, you'd be able to see it perfectly well - just as clear as it appears on your computer monitor in Celestia. (If you were sitting on Pluto, you'd be able to read a book by the light of the Sun.)

Does it bother you when you watch TV, that indoor and outdoor scenes appear equally bright? Of course not. But the contrast is pretty much exactly the same as that between Earth and Pluto - there's about a thousand-fold decrease in illumination when you come indoors from direct sunlight to artificial light. But your eyes adapt so quickly you barely notice it, and you certainly wouldn't thank film-makers if they under-lit their indoor scenes to make them a thousand times dimmer on your TV screen (hey, it's more "realistic"). Exactly the same applies to Pluto - your eyes would adapt, and it just wouldn't look noticeably dimmer when you were there.

I take your point about the extreme case a light-year from the Sun - but this side of the Kuiper belt, realism is better maintained if Celestia doesn't decrease the apparent brightness of objects with increasing distance from the Sun.

Grant

[Guest]

No, it isn't like that in real life. That's my whole point - if you were in orbit around Pluto right now, you'd be able to see it perfectly well - just as clear as it appears on your computer monitor in Celestia. (If you were sitting on Pluto, you'd be able to read a book by the light of the Sun.)

The intensity of light is inversely proportional to the square of the distance. Therefore, since pluto is 30 times futher from the sun than the earth is (today), the light that hits it is 1/900th as bright as the light that hits the earth. I feel that it should be this way in celestia. and i also doubt that it would be possible to read a book in 1/900th the light.

[guest]

and to correct myself in my first post at the top of the page, it was a 30 MINUTE exposure insead of 30 second.

[Evil Dr Ganymede]

The intensity of light is inversely proportional to the square of the distance. Therefore, since pluto is 30 times futher from the sun than the earth is (today), the light that hits it is 1/900th as bright as the light that hits the earth. I feel that it should be this way in celestia. and i also doubt that it would be possible to read a book in 1/900th the light.

Ever tried reading something by the light of the full moon on a clear night? I can do it with no problem. That's a lot dimmer than 1/900th of the light from the sun. In fact, the light reaching the earth's surface (in lux) that bounces off the full moon is about 0.2 lux, and the light from the sun is about 100,000 lux, so that's a different of a factor of 500,000.

So 1/900th of the light is still pretty darn bright, really. It'd be over 550 times brighter than the full moon.

[guest]

all im saying is that pluto should be 1/900 dimmer in celestia. Right? do you agree?

[granthutchison]

all im saying is that pluto should be 1/900 dimmer in celestia. Right? do you agree?

No! And I've already done my best to explain why.

Grant

[Christophe]

Strangely this thread reminds me of another one on the size of the full moon...

[t00fri]

My impression has been repeatedly in such discussions that some people simply do not read and /digest/ what has been written!

Grant did such an excellent job in explaining what is going on here. How is it possible that the same erroneous claims keep coming back and back and back...?;-)

Bye Fridger

[chris]

I'm going to update the 'official' FAQ with Grant's and Selden's answers . . . Not that I think it will help too much

--Chris

[selden]

My impression has been repeatedly in such discussions that some people simply do not read and /digest/ what has been written!

Grant did such an excellent job in explaining what is going on here. How is it possible that the same erroneous claims keep coming back and back and back...?;-)

Bye Fridger

A man convinced against his will
is of the same opinion still.

[tommy sixpix]

To Grant and Gordon....I want to thank you very much for your answers, exactly what I was looking for! ...on a side note...there seems to be alot of arguing in this forum...I.E. problems with the BORG and GUESTS complaining about a FREE program...I have only had this program for a few weeks now and I think it is wonderful...and the fact that it is FREE is definately a bonus...I have children, and I have found it best not to stoop to thier level when it comes to childish arguments...state the facts, how ever they may be, and leave it at that...continuing to argue with them only empowers them...My oppologies in advance for those that I offend by these statements...I remember when I was a teenager, and I had the answers for everything.......
Sincerly, Tommy