[TigersEye]

The sun has set from the POV of the camera, but not from the POV of the contrail which is both miles west toward the sun, but more importantly probably ~30,000 feet higher than the camera. So you see the sun light reflecting off the bottom of the contrail.

In that case then the furthest west point of the contrail would be the last part to fall into shadow.

As you can see there the "farthest west," or bottom, of the contrail is the first to fall into shadow. It also passes in front of a line of clouds in the distance. If it were an airplane at 30k ft coming from the horizon it would pass over that relatively near and low line of clouds.

[Wayne07]

Actually, if you look at the photo, you can se the reflection is the brightest at the bottom of the contrail. You aren’t see it fall into shadow at all, the darkness across the full width of the bottom is low level haze in the foreground.

[RobRoy]

>>In that case then the furthest west point of the contrail would be the last part to fall into shadow.<<

It is not falling into shadow. It is being blocked by thin haze, and quite a few miles of it, since it is so close to the horizon.

I was just in Hawaii and watched the sun do the exact same thing, regarding the haze. But since it is the sun, nobody interprets its reduction in light as “falling into shadow”.

People are looking at these videos with only one paradigm in mind. Try looking at the pictures and video and intentionally assume it is a rocket, and then try the same thing but intentionally assume it is an airplane. It should become pretty obvious to you which it is at that point. It did for me.