33 replies to this topic

[Tony Flanders]

Grackles have some kind of optical thing going on in their feathers.

It's called iridescence, caused by interference effects. Quite common in nature.

[star69]

I never really liked either of those bands.


 

-Kevin

[gnowellsct]

Scientific wise yes. But we often call Starlings, 'grackles' in Ireland.
I believe true Grackles are native only to the Americas.

There's no science about it. At times they fill my backyard. They are grackles and they know it and I know it and even the dog knows it.

[gnowellsct]

It's called iridescence, caused by interference effects. Quite common in nature.

Yes. And common in grackles.

[Princess Leah]

I must give my sincere condolences to any other Grackle lovers reading the post.

My deepest and most profound apologies for any nomenclature mistakes on my part.

Edited by Princess Leah, 18 December 2024 - 04:33 AM.

[Echolight]

Well, Greg did think that I must have been looking at grackles when I said many black birds have a purple tinge. When in fact I was talking about crows, ravens, and males of the common blackbird species.

 

But that's ok. Lots of birds have iridescent feathers though. Ducks, pigeons, and others. But these are generally not as evenly shiny as those from the family which one of our constellations is named for.

[Princess Leah]

If you have chromatic aberation, only certain colors are "misplaced".

A white seagull is a brighter than the blue sky. So if some "misplaced" blue sky is added to the bright white - it adds up to only a slighty shifted color. The red and green in the birds white is all still where it needs to be.

On the dark crow, you see essentially mostly just the "misplaced" color. As not much is added to it by the bird at all. So the overall color of that bird has about the same color saturation than the misplaced light. Which is a pretty pure blue.

 

Thats why you see any color fringing more pronunced on the darker side of any high contrast edge.

Very well explained!

[Wildetelescope]

 

The sky is bright, the seagulls are bright, low contrast.  

 

The sky is bright, the crow is very dark, that's high contrast. A darl object silhouetted against the blue sky shows CA...  

 

 

 

Jon

 

So it is essentially the same reason you see CA on the moon at the edge of its limb and in craters/ mountains along the terminator?   High contrast areas.   

 

JMD

[Princess Leah]

Jon is also right about my snow observation, when looking at snow-capped mountains on the horizon.

The snow is very bright/highly reflective - the blue sky not that bright in comparison. (The sky is not as bright as I think, at a distance of twenty miles).

 

I think snow must be one of the brightest/most-white things in nature.