sep 5, 1951 - Aug/Sept 1951 Lubbock Lights Professor "observed one formation of lights flying above a thin cloud at about 2,000 feet which he says allowed them to calculate that the lights were traveling at over 600 miles per hour"
Description:
https://en.wikipedia.org/wiki/Lubbock_LightsAdded to timeline:
Date:
sep 5, 1951
Now
~ 74 years ago