UFO in Maryland with Inverted Umbrella Shape

Summary

Three objects shaped like inverted umbrellas with a glowing amber light were sighted in Maryland in 1957. They moved in a single file without leaving a trail, at a speed of 120 mph, suggesting they could be light planes simulating artificial satellites. The detailed description and the "throbbing glow" align with aerial training activities of the time. Though not conclusively identified, the clues point to a terrestrial explanation.