High School What Color Do Mirrors on Earth Appear from Space?

Click For Summary
Observers in space would primarily see a mirror on Earth reflecting the blue sky due to Rayleigh scattering, which enhances blue light. The discussion highlights that while the mirror reflects direct sunlight, it also captures scattered light from the atmosphere, leading to a predominantly blue appearance. Some participants speculate about potential red hues based on atmospheric effects, but the consensus leans towards blue being the dominant color observed. The conversation also touches on how shadows on Earth appear blue due to the same scattering effects. Ultimately, the mirror's reflection would not show red, but rather a blue-tinted image influenced by atmospheric conditions.
  • #31
I think black from the space will make bluish tint very hard to see
 
Physics news on Phys.org
  • #32
Curiosity_0 said:
I think black from the space will make bluish tint very hard to see
Then why does the sky look blue against the black of space, when viewed from Earth.
 
  • #33
Curiosity_0 said:
I think black from the space will make bluish tint very hard to see

The Earth's surface will be next to the mirror - not the black of space. The 'background' the observer will be comparing the mirror image with will be surrounding land which could be darker or lighter than the patch of blue sky image that's reflected. That would / could depend on the inclination of the Sun and the proportion of the land that is shadow.
The "black from space" would be at the edge of the observer's vision and I don't think it would actually count in the colour perception of that mirror image.
 
  • #34
There are many solar power plants using large mirrors on earth. Their color as seen from the satellite is blue.
solare.jpg

(source google maps: planta solar 10 Spain)
I have another question: if I have a photo of the sky taken with a smartphone, can I get physically meaningful data from the colors in the picture? Or can the RGB matrix I get cannot be used for anything?
 
  • Like
Likes sophiecentaur
  • #35
accdd said:
I have another question: if I have a photo of the sky taken with a smartphone, can I get physically meaningful data from the colors in the picture? Or can the RGB matrix I get cannot be used for anything?
There is useful information. In particular you get three numbers (R,G,B). The exact calibration of these numbers will be far more useful if you have a white (or known uniform gray) image and perhaps a "black" image. Of course if you have a JPEG or other compression scheme it is more complicated.
 
  • #36
accdd said:
There are many solar power plants using large mirrors on earth. Their color as seen from the satellite is blue.
View attachment 317079
(source google maps: planta solar 10 Spain)
I have another question: if I have a photo of the sky taken with a smartphone, can I get physically meaningful data from the colors in the picture? Or can the RGB matrix I get cannot be used for anything?
A picture speaks a thousand words! I’m embarrassed that someone else thought of posting one.
I’d just add that a long trip up through the atmosphere would reduce the blue/green component and pull the resultant towards the original 6k(ish) white from the Sun.

My only question would be whether that image is actually from a satellite. I remember reading that a lot of the original Google images were in fact from surveillance aircraft

Plus the possible colour balancing of the Google images could have purposely biased the images to ‘look like’ we’re used to. But the point is more or less proved that what is seen up there is ‘a sky blue’. 🙂👍🏼
 

Similar threads

  • · Replies 7 ·
Replies
7
Views
5K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 26 ·
Replies
26
Views
2K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 13 ·
Replies
13
Views
3K
  • · Replies 45 ·
2
Replies
45
Views
5K
Replies
7
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 22 ·
Replies
22
Views
2K
Replies
6
Views
2K