It’s obviously a reflection, even more because it’s there sometimes, and not others. A rocket motor would be constant ~and~ bigger.Here is a video of a shuttle launch taken at very close range. The shuttle has two solid rocket motors each of which is much bigger than an ICBM motor. At about 1:30 into the video why can't we see any glow from the motors? It "would be constant" right?
NASA Last Shuttle Launch For Columbia
Photos from a shuttle launch video for comparison:
30 seconds into launch, over 3 miles altitude. Note the tight exhaust trail.
40 seconds later, rocket has gone 17 miles higher - over 20 miles in altitude. Serious fire from the rockets - no doubt, no dull redish reflection appearing briefly then disappearing.
Solid booster rocket separation:
And finally, three minutes after launch, extreme zoom sees the fire end of the rockets disappearing, traveling over 2,600 miles per hour.
