A Big Bright Spot

On our trip to Utah this past March, I did what I usually do, looked out the airplane window.

And I saw this, a big bright spot.

A big bright spot that traveled along with us, moving across the landscape below. You can see for yourself in this linked video. (Warning, this is just a boring video of a barely visible bright spot moving across the farm fields in the center of the image. Enjoy!)

This is an example of the Opposition Effect. This occurs when looking at the anti-solar point, as the shadows cast by objects in that direction are completely behind those very same objects. And are thus blocked from the viewer. This lack of shadows makes the area appear brighter than its surroundings.

Click here for an explanation of the phenomena (as always for anything optics related, it is from Les Cowley's excellent Atmospheric Optics site).

Here is another video, this one showing a dark spot surrounded by a subtle glow moving across the ground. In this case the plane is lower in altitude so we can see its shadow.

☁️  ☁️  ☁️  ☁️  ☁️

Of course, to observe such phenomena the sky needs to be clear. Earlier in the flight it was cloudy, as shown in the image below. And the Opposition Effect was not visible.

No doubt hidden behind that Glory.