Actually, I'm having a bit of trouble pinpointing where this picture should be in the sequence (2.5 or 4). This picture was shot much closer to the Tower and closer to the ground than the video sequence from Fox News. The explosion appears larger in this pic, which would mean that it was taken a fraction of a second later and thus would be No. 4 in the sequence. But we're seeing the underside of the explosion which can create the illusion of the ball of flame being larger. However, the dark spots on the top of the explosion in the Fox video are more prevalent, indicating a later stage. Comparing other aspects of the two photos is difficult because of the grainy quality of the Fox News/Gamma Press video.
Because certainty about this picture is as shadowy as the object itself, I draw no conclusions. The blue/green smoke seen here could be residual evidence of the "vortex snake" created as the object flew through the smoke; or it could be a patch of smoke from something combustible other than jet fuel within the tower. However, just below this pic is another very clear shot of the explosion taken an instant later from a slightly different angle: In that picture, the blue/green shadow is gone.
To facilitate comparison, I've enhanced a frame from the Fox sequence by adjusting the color and saturation to approximate the colors in the higher quality photo. Both pictures - and all pictures on this site - are here for you to make of them what you will.
