Blazars are a particular kind of very variable quasar, viewed from Earth down the axis of a relativistic jet — a beam of accelerated ionized matter. One possible explanation for the extreme variability in radiation flux from blazars is changes in the viewing angle.
Claudia Raiteri and collaborators report observations from radio to optical wavelengths of the blazar CTA 102 during a recent extreme outburst, where its optical brightness increased by six magnitudes. They conclude that the variability they see is consistent with a twisting, inhomogeneous jet whose components change their viewing angles, like a firehose blasting out water that twists when not held.