Intensity of light along the iridium flare

In summary, the conversation discusses the phenomenon of iridium flares and attempts to understand why the bright spot on Earth's surface is not of the same intensity. One theory is that the sun is not a point-like light source, causing a changing fraction of its disc to not reflect directly to the observer. The conversation also includes a diagram to further explain the situation.
  • #1
jojotank
13
0
Hello.
I have some question about iridium flares. My brains can' t process the whole picture.

Iridium panell works like a mirror and reflects quite some percantege of light to the Earth's surface, where it makes a bright spot with quite a big radeous. An observer sees a bright spot in the sky which is gradually becoming larger and then again slower, until you don t see it anymore. I can t understand why.

Why don' t we see just a momentary flash? Similar to when somone is annoying us with a watch which reflects sunlight into our eyes.

I was thinking that maybe it is because of rotation of the panell. I understand that if the angle of incidence is big, then the intensity will be smaller (changing with cosine function right ?). But then i thought that just a small change in the angle of panell would move this spot far away of the observer's position.

I was also thinking that it may have something to do with atmosphere, scattering of light and all. But i don't believe that would be the case.

My conclusion is that this spot on Earth surface is not of the same intensity - getting smaller towards the edges. But i don' t understand why.

I would be so glad if someone explains it a bit. I can't stand this enigma anymore :)

Thank you so much, and sorry for my english.
 
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  • #2
One factor (though likely not the only factor) is that the sun is not a point-like light source. As the panel moves into and out of position, a changing fraction of its disc is not reflecting directly to you.
It is the same effect that causes the penumbra of an eclipse.

ole3.gif


penumbraphoto.jpg
 
  • #3
Like so:

light.png
 
  • #4
Thank you so much!

I understand it perfectly now. I had some ideas when i was looking at the solar eclipse dark spots on the Earth surface, but i wasn't able to drive it to the end. Thank you so much. I don't want to bi nagging and annoying and i hope you will excuse. Light intensity graph is more like this right?

light.png


Thank you again! I would be smashing my head for a while if you wouldn't help.
 
  • #5
jojotank said:
Light intensity graph is more like this right?
View attachment 84903
Yes. PhotoShop doesn't do curved lines easily. :wink:
 
  • #6
Hello Dave, i hope you will be reading this. I just wanted to aks you if this diagram is correct when explaining whole situation. Do you think there should be any corrections?
Thank you :)

internet 2.png
 

Related to Intensity of light along the iridium flare

1. What is an iridium flare?

An iridium flare is a bright, brief burst of light that occurs when sunlight reflects off of the antennas of satellites in the Iridium communications network as they pass over a specific location on Earth.

2. How is the intensity of light along an iridium flare measured?

The intensity of light along an iridium flare is measured in magnitudes, using a scale known as the Iridium Flare Index (IFI). The lower the magnitude, the brighter the flare will appear in the sky.

3. What factors affect the intensity of light along an iridium flare?

The intensity of light along an iridium flare can be affected by the angle and position of the satellite as it reflects sunlight, as well as the atmospheric conditions, such as the amount of cloud cover or pollution in the sky.

4. Can the intensity of light along an iridium flare be predicted?

Yes, the intensity of light along an iridium flare can be predicted using calculations and data from the satellite's orbit and position, as well as the location and time of the observer on Earth. However, unexpected changes in atmospheric conditions can affect the actual brightness of the flare.

5. How can I see an iridium flare?

To see an iridium flare, you can use online prediction tools or mobile apps to find out when and where one will occur in your location. Then, go outside and look in the predicted direction at the predicted time. Make sure to find a dark area with minimal light pollution for the best viewing experience.

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