Spectacular BECO cutoff during Starliner launch

NASA and Boeing launched the Starliner Commercial Crew space craft yesterday. One of the stages is BECO cutoff where the main booster detaches from the rocket, prior to the Centaur engine starting up, and pushing Starliner into orbit.

There’s an awesome view of the rocket from the ground that shows this spectacular effect at BECO cutoff:

You can see this in the NASA video around now: