by Ann » Thu Oct 20, 2022 3:57 am
johnnydeep wrote: ↑Wed Oct 19, 2022 9:45 pm
Chris Peterson wrote: ↑Wed Oct 19, 2022 5:12 pm
Ann wrote: ↑Wed Oct 19, 2022 4:06 pm
Not sure I get you there, Chris. Obviously grass is brilliantly bright when the Sun seems to shine right through it. But then the grass is between you and the Sun and the Sun is in front of you and behind the grass. Isn't the grass in front of you less bright when the Sun is behind you?
When the Sun is behind you, the light coming from the grass is mainly reflected, and only a small part of the total visible spectrum comes back. When the Sun is almost behind the grass, a lot of light is scattered, and that represents the entire spectrum. This is why grass and leaves are often much brighter when they are backlit than when they are front lit. Usually, the light that comes through the leaves themselves isn't a major component of the total intensity.
You've blown my mind once again, Chris! The images shown here seem to show the effect you're talking about:
http://spacecraftkits.com/scatter/
Thanks, Johnny, that's a great illustration! We might want to look at backlit Saturn, too:
It is interesting that the far side of Saturn is not dark, because it is being lit up by its own rings. But it is only the "upper part" of Saturn that is lit up, because that is where the rings are passing in front of it. "The other side of the rings" are "on the other side of Saturn". The contour of Saturn, its upper atmosphere, is brilliantly lit by the Sun.
It is interesting to see the colors of the brilliantly lit rings. The inner, bright rings are very yellow. The outer E ring is very blue. However, it is bluest "above" and "below" the disk of Saturn, where it is also brightest. Off to the right, it isn't very blue. Why does its hue vary? Or maybe the hue stays the same, and it is just the saturation that varies?
There is another ring between the E ring and the bright inner ring that is reasonably blue, too. And there is one ring, separated from the bright A ring by a narrow gap, that is brilliantly white.
Well, I guess it all has to do with the size of the particles in the rings and the way these particles scatter light.
Ann
Ann
[quote=johnnydeep post_id=326663 time=1666215932 user_id=132061]
[quote="Chris Peterson" post_id=326654 time=1666199554 user_id=117706]
[quote=Ann post_id=326651 time=1666195593 user_id=129702]
Not sure I get you there, Chris. Obviously grass is brilliantly bright when the Sun seems to shine right through it. But then the grass is between you and the Sun and the Sun is in front of you and behind the grass. Isn't the grass in front of you less bright when the Sun is behind you?
[/quote]
When the Sun is behind you, the light coming from the grass is mainly reflected, and only a small part of the total visible spectrum comes back. When the Sun is almost behind the grass, a lot of light is scattered, and that represents the entire spectrum. This is why grass and leaves are often much brighter when they are backlit than when they are front lit. Usually, the light that comes through the leaves themselves isn't a major component of the total intensity.
[/quote]
You've blown my mind once again, Chris! The images shown here seem to show the effect you're talking about:http://spacecraftkits.com/scatter/
[/quote]
Thanks, Johnny, that's a great illustration! We might want to look at backlit Saturn, too:
[img3=""]https://solarsystem.nasa.gov/system/resources/detail_files/17706_Saturn_Backdrop_1600.jpg[/img3]
It is interesting that the far side of Saturn is not dark, because it is being lit up by its own rings. But it is only the "upper part" of Saturn that is lit up, because that is where the rings are passing in front of it. "The other side of the rings" are "on the other side of Saturn". The contour of Saturn, its upper atmosphere, is brilliantly lit by the Sun.
It is interesting to see the colors of the brilliantly lit rings. The inner, bright rings are very yellow. The outer E ring is very blue. However, it is bluest "above" and "below" the disk of Saturn, where it is also brightest. Off to the right, it isn't very blue. Why does its hue vary? Or maybe the hue stays the same, and it is just the saturation that varies?
There is another ring between the E ring and the bright inner ring that is reasonably blue, too. And there is one ring, separated from the bright A ring by a narrow gap, that is brilliantly white.
Well, I guess it all has to do with the size of the particles in the rings and the way these particles scatter light.
Ann
Ann