Pulsing light, moving across the sky.

Pulsing light, moving across the sky.
Time: 6:35 PM

Location: Inland Empire, CA

I was out front with the dogs and noticed a pulsing light, moving across the night sky, from SE to NW. I'm in Southern California and I make a habit of surveying the sky, every chance I get. I've seen the ISS and satellites, and this was neither. It wasn't catching the suns light, it was actually pulsing every two seconds. It was far too high to be a plane and only had one white light. I ran inside to get my wife and she was at a loss, as well. We're stumped.

Does anyone have any idea what we might have seen?