Arcing across coil terminals

Car didn't want to idle right today, popped hood and noticed a loud clicking sound.

The ignition coil positive and negative leads are (both alternating) arcing with the distributor lead. The connections are all firmly attached, clean new hardware, and the distributor wire is firmly seated in with a dust boot. What gives? Why is the ignition arcing all the sudden?

Standard points on a 360. Ballast resistor installed, Standard UC12x coil with a factory distributor.