Bright white light silently moving East to West at impossible speed back at least 6 times over 30 minute period.

Last evening whilst sitting the garden looking North. I noticed a bright white shimmering light moving East to West in the blink of an eye but no sound. I went in the house and explained to my wife what I’d seen, she rather sceptically went out side to look, and after a couple of minutes, witnessed the same thing only travelling West to East. My son also came outside and we all witnessed the same again but travelling East to West and this too and fro continued, intermittently, for around 30 minutes. It wasn’t a plane or helicopter as it was silent and travelling at tremendous speed. My son tried to record it on his phone, but just a dull green shape appears in a single frame.