I've seen burns under somewhat more unusual circumstances. Besides the obvious first stage burns from launch through when the rocket goes out of site .... If a launch occurs before dawn or after sunset then the geometry results in the rocket launching from darkness in to sunlight once it gets above the Earth's shadow. Under these conditions the second stages of the Deltas and Atlases are *extremely* impressive to view - a wispy cloud which expands gradually - almost like a supernova remnant in appearance. The exhausts do the same thing on every launch, but it's only when the exhaust products are in sunlight and the sky's still fairly dark that this phenomena is visible. More often than not there are reports that the rocket has blown up - even though it's functioning perfectly. Philip Chien, KC4YER Earth News world (in)famous writer, science fiction fan, ham radio operator, all-around nice guy, etc.