The bundle of data was packed up and sent to Project Blue Book. The panel of experts convened.
First, the radarscope photos were examined.
"Those targets could be interference from other radars," said the radar expert, and he mentally ticked off a dozen and one other similar cases of known interference. The weather data, and locations and frequencies of other radars were checked out.
Beyond doubt it was interference from another radar that caused the target.
Now, the visual sighting.
Balloon? No, the fighters could have caught a balloon in seconds.
Airplane? Same answer. These jets were the fastest things in the air.
Planet or star? Out came the almanacs and the puzzle went to the astrophysicist. Venus was on a bearing of 300 degrees from the Duluth Municipal Airport at 5:20P.M. on March 23rd. But Venus was just below the horizon at that time and the observers said the UFO was "moving fast."
Once again the weather charts were studied. The atmospheric conditions were such that it was very possible that due to refraction Venus would have been visible just on the horizon. The fact that the UFO faded so fast would bear this out because the conditions for such refraction are critical and a slight change in atmospheric conditions could easily have caused the planet to disappear.
The speed—a common illusion. Further interrogation of the observers showed it had never moved.