The Impossible Result

[Tuur]

All right: This is something that's bugging me. It doesn't involved conspiracy theories or anything off-the-wall. Just simple trigonometry and atmospheric effects. And it's really bugging me.

One evening 1:06 minutes after sunset, I happened to observe a trail in the west illuminated by the sun. Have once observed a meteor that left a trail, and a fireball, but there was no light at the leading end. That meant it could have been an airplane contrail. It was rather pretty, particularly at one point when it brightened and scintillated, then it dimmed.

At that point I was struck with an idea: If I could estimate the angular elevation when the trail winked out, I could estimate the altitude.

The problem is, the result would put it in a low earth orbit. That's impossible because of two things:

1. It was showing atmospheric effects
2. The trail had a visible width

I've gone over my calculations again and again, with the same result.

Embarrassingly belatedly it hit me that it wouldn't suddenly become invisible when the sun was below the horizon relative to the trail. It should have remained visible for a time afterward for the same reason it's not completely dark minutes after sunset.

Thoughts on this? Besides that I really need to be finding something to do. Right now I'm thinking about two things:

1. When the trail winked out would have been when it was as dark or darker than it was at my location. That would mean the sun was about 16.5° below the object's horizon.
2. When the trail brightened was when sunlight was directly reflected toward me. That gives an angle of reflection, but one that's to my own horizon.

 

[SelfSim]

Don't worry about it. The President took care of it.
It was a Chinese spy balloon bein' taken out by a missile.

 

[sjastro]

All right: This is something that's bugging me. It doesn't involved conspiracy theories or anything off-the-wall. Just simple trigonometry and atmospheric effects. And it's really bugging me.

One evening 1:06 minutes after sunset, I happened to observe a trail in the west illuminated by the sun. Have once observed a meteor that left a trail, and a fireball, but there was no light at the leading end. That meant it could have been an airplane contrail. It was rather pretty, particularly at one point when it brightened and scintillated, then it dimmed.

At that point I was struck with an idea: If I could estimate the angular elevation when the trail winked out, I could estimate the altitude.

The problem is, the result would put it in a low earth orbit. That's impossible because of two things:

1. It was showing atmospheric effects
2. The trail had a visible width

I've gone over my calculations again and again, with the same result.

Embarrassingly belatedly it hit me that it wouldn't suddenly become invisible when the sun was below the horizon relative to the trail. It should have remained visible for a time afterward for the same reason it's not completely dark minutes after sunset.

Thoughts on this? Besides that I really need to be finding something to do. Right now I'm thinking about two things:

1. When the trail winked out would have been when it was as dark or darker than it was at my location. That would mean the sun was about 16.5° below the object's horizon.
2. When the trail brightened was when sunlight was directly reflected toward me. That gives an angle of reflection, but one that's to my own horizon.

What was the colour of the trail?

 

[Tuur]

What was the colour of the trail?

White. The color changed with the position, becoming yellowish at its brightest.

FWIW, have observed several rocket launches over the years, and those you could follow by the glow of the engines stopped leaving a trail once it left the atmosphere. That's another indication that I'm not taking something into account: if my calculations were correct, there should have been no trail at all.

Started tinkering around with the normal airliner cruising altitude of 36,000 feet / 11,000 meters. Will see where that leads.

 

[Tuur]

Update:

If the trail was at 36,000 feet / 11,000 meters, the sun in respect to the point where it the trail disappeared would have been about 13° below the horizon from the POV of the trail. Nautical twilight ends in the evening when the sun is 12° below the horizon. That is likely the problem with my initial calculations: I had assumed the trail vanished when the sun was below the horizon relative to it. It likely had enough illumination to be visible even though it was in twilight.

The interesting implication is for high altitude clouds. They would likely show the same effect. Something to watch for at sunrise or sunset.