A supposed star, at a time before there were humanly created objects in orbit, which behaved very differently from the other stars.
In July of 1957, I was a cadet at the Air Force Academy which was then located at the temporary site at Lowry Air Force Base on the outskirts of Denver.
At the time of the sighting, I was taking practice celestial fixes pursuant to becoming an Air Force navigator.
The exact date escapes me, but it was in July.
There were celestial navigation trainers in the quadrangle, small enclosures with astrodomes inside, that each of us used with a bubble sextant hung from an astrodome.
The sextants were 1.5 power and were pre-set by the student for azimuth and elevation.
Once the settings were in the sextant, the student would look into the eyepiece and choose the brightest star in the field to set the sextant cross-hairs and hold them there for two minutes.
The 2 minutes was necessary for the sextant averager to arrive at the proper elevation for the precomputed time of the shot.
On this night, I had precomputed a shot for Kochab in the Little Dipper, set the proper azimuth and elevation into the sextant, and had set the cross hairs on the bright star in the field.
I began the shot and was adjusting the elevation as the averager was ticking away.
The star I was shooting held firm with other stars in the field for about half minute.
Then I noticed that the azimuth and elevation were changing in excess of what was usual and could see that the supposed star was changing location relative to the other stars in the field.
I took my eye from the eyepiece and watched the star slowly moving to the right and slightly downward in relation to the other stars.
There were 2 other cadets in the trainer precomputing for a shot.
I tried to show them the star, but they could not easily see it among the other stars and it was moving too slowly for them to notice it easily, so they lost interest quickly and never saw what I was attempting to show them.
I was not excited because nothing exciting seemed to be happening.
Consequently, the other cadets went back to what they had been doing.
I watched the star continuing to move for a distance of about 10° across the sky, perhaps it was less.
And then it stopped and just stayed in place with the other stars once more.
I continued to watch the star for several minutes and checked its location again before I left the trainer, at least a half hour later.
The object never moved again during this time relative the other stars.
I thought about this for some time.
I never reported it.
This was before there was ever even a Sputnik.
Later, in the Air Force, I learned of many UFO sightings that were never reported, reporting them was unwise at the time.
And I began to think that what I had seen was a mother ship changing its solar orbit, otherwise, it would have been moving all the time.